Kallikrein-binding &#34;kunitz domain&#34; proteins and analogues thereof

ABSTRACT

This invention provides: novel protein homologous of a Kunitz domain, which are capable of binding kallikrein; polynucleotides that encode such novel proteins; and vectors and transformed host cells containing these polynucleotides.

RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 09/421,097, filed Oct. 19, 1999, now allowed; which is a division of U.S. application Ser. No. 08/208,264, filed Mar. 10, 1994, now U.S. Pat. No. 6,057,287; which is a continuation-in-part of U.S. application Ser. No. 08/179,964, filed Jan. 11, 1994, now abandoned, the entirety of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to novel classes of proteins and protein analogues which bind to and may inhibit kallikrein.

2. Description of the Background Art

Kallikreins are serine proteases found in both tissues and plasma. Plasma kallikrein is involved in contact-activated (intrinsic pathway) coagulation, fibrinolysis, hypotension, and inflammation. (See Bhoola, et al. (BHOO92)). These effects of kallikrein are mediated through the activities of three distinct physiological substrates:

-   -   i) Factor XII (coagulation),     -   ii) Pro-urokinase/plasminogen (fibrinolysis), and     -   iii) Kininogens (hypotension and inflammation).         Kallikrein cleavage of kininogens results in the production of         kinins, small highly potent bioactive peptides. The kinins act         through cell surface receptors, designated BK-1 and BK-2,         present on a variety of cell types including endothelia,         epithelia, smooth muscle, neural, glandular and hematopoietic.         Intracellular heterotrimeric G-proteins link the kinin receptors         to second messenger pathways including nitric oxide, adenyl         cyclase, phospholipase A₂ and phospholipase C. Among the         significant physiological activities of kinins are: (i)         increased vascular permeability; (ii) vasodilation; (iii)         bronchospasm; and (iv) pain induction. Thus, kinins mediate the         life-threatening vascular shock and edema associated with         bacteremia (sepsis) or trauma, the edema and airway         hyperreactivity of asthma, and both inflammatory and neurogenic         pain associated with tissue injury. The consequences of         inappropriate plasma kallikrein activity and resultant kinin         production are dramatically illustrated in patients with         hereditary angioedema (HA). HA is due to a genetic deficiency of         C1-inhibitor, the principal endogenous inhibitor of plasma         kallikrein. Symptoms of HA include edema of the skin,         subcutaneous tissues and gastrointestinal tract, and abdominal         pain and vomiting. Nearly one-third of HA patients die by         suffocation due to edema of the larynx and upper respiratory         tract. Kallikrein is secreted as a zymogen (prekallikrein) that         circulates as an inactive molecule until activated by a         proteolytic event. Genebank entry P03952 shows Human Plasma         Prekallikrein.

Mature plasma Kallikrein contains 619 amino acids. Hydrolysis of a single Arg-Ile bond (at positions 371-372) results in the formation of a two-chain proteinase molecule held together by a disulfide bond. The heavy chain (37.1 amino acids) comprises four domains arranged in sequential tandems of 90-91 residues. Each of the four domains is bridged by 6 half-cysteine residues, except the last one, which carries two additional half-cysteine residues to link together the heavy and light chains. These domains are similar in sequence to factor XI. The light chain (248 residues) carries the catalytic site, and the catalytic triad of His-415, Asp-464 and Ser-559 is especially noteworthy.

The most important inhibitor of plasma kallikrein (pKA) in vivo is the C1 inhibitor; see SCHM87, pp. 27-28. C1 is a serpin and forms an irreversible or nearly irreversible complex with pKA. Although bovine pancreatic trypsin inhibitor (BPTI) (SEQ ID NO:1) was first said to be a strong pKA inhibitor with K_(i)=320 pM (AUER88), a more recent report (Berndt, et al., Biochemistry, 32:4564-70, 1993) indicates that its Ki for plasma Kallikrein is 30 nM (i.e., 30,000 pM). The G36S mutant had a Ki of over 500 nM.

“Protein engineering” is the art of manipulating the sequence of a protein in order to alter its binding characteristics. The factors affecting protein binding are known, but designing new complementary surfaces has proved difficult. Although some rules have been developed for substituting side groups, the side groups of proteins are floppy and it is difficult to predict what conformation a new side group will take. Further, the forces that bind proteins to other molecules are all relatively weak and it is difficult to predict the effects of these forces.

Nonetheless, there have been some isolated successes. Wilkinson et al. reported that a mutant of the tyrosyl tRNA synthetase of Bacillus stearothermophilus with the mutation Thr₅₁-Pro exhibits a 100-fold increase in affinity for ATP. Tan and Kaiser and Tschesche et al. showed that changing a single amino acid in a protein greatly reduces its binding to trypsin, but that some of the mutants retained the parental characteristic of binding to an inhibiting chymotrypsin, while others exhibited new binding to elastase.

Early techniques of mutating proteins involved manipulations at the amino acid sequence level. In the semisynthetic method, the protein was cleaved into two fragments, a residue removed from the new end of one fragment, the substitute residue added on in its place, and the modified fragment joined with the other, original fragment. Alternatively, the mutant protein could be synthesized in its entirety.

With the development of recombinant DNA techniques, it became possible to obtain a mutant protein by mutating the gene encoding the native protein and then expressing the mutated gene. Several mutagenesis strategies are known. One, “protein surgery”, involves the introduction of one or more predetermined mutations within the gene of choice. A single polypeptide of completely, predetermined sequence is expressed, and its binding characteristics are evaluated.

At the other extreme is random mutagenesis by means of relatively nonspecific mutagens such as radiation and various chemical agents, see Lehtovaara, E.P. Appln. 285,123, or by expression of highly degenerate DNA. It is also possible to follow an intermediate strategy in which some residues are kept constant, others are randomly mutated, and still others are mutated in a predetermined manner. This is called “variegation”. See Ladner, et al. U.S. Pat. No. 5,220,409.

The use of site-specific mutagenesis, whether nonrandom or random, to obtain mutant binding proteins of improved activity, is known in the art, but does not guarantee that the mutant proteins will have the desired target specificity or affinity. Given the poor anti-kallikrein activity of BPTI, mutation of BPTI or other Kunitz domain proteins would not have been considered, prior to the present invention, a preferred method of obtaining a strong binder, let alone inhibitor, of kallikrein.

SUMMARY OF THE INVENTION

The present invention relates to novel Kunitz domain proteins, especially LACI homologues, which bind to, and preferably inhibit, one or more plasma (and/or tissue) kallikreins, and to the therapeutic and diagnostic use of these novel proteins.

A specific, high affinity inhibitor of plasma kallikrein (and, where needed, tissue kallikrein) will demonstrate significant therapeutic utility in all pathological conditions mediated by kallikrein, and especially those associated with kinins. The therapeutic approach of inhibiting the catalytic production of kinins is considered preferable to antagonism of kinin receptors, since in the absence of kallikrein inhibition, receptor antagonists must compete with continuous kinin generation. Significantly, genetic deficiency of plasma kallikrein is benign and thus, inhibition of plasma kallikrein is likely to be safe. We have recently discovered a lead pKA inhibitor, designated KKII/3#6 (SEQ ID NO:7). This inhibitor is a variant of a naturally occurring human plasma protein Kunitz domain and demonstrates significantly greater kallikrein binding potency than Trasylol. KKII/3#6 (SEQ ID NO:7) has a Ki for kallikrein which is over 100 times that of both wild-type LACI (SEQ. ID NO:25) and of BPTI (SEQ ID NO:1), and is in the nanomolar range. In contrast, its Ki for plasmin is 10 uM. A reversible inhibitor is believed to be of greater utility than an irreversible inhibitor such as the C1 inhibitor.

The present invention also relates to protein and non-protein analogues, designed to provide a surface mimicking the kallikrein-binding site of the proteins of the present invention, which likewise bind kallikrein. These are termed “conformational analogues.”

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows six pseudopeptide bonds, in each figure, R₁ and R₂ are the side groups of the two amino acids that form the pseudodipeptide. If, for example, the dipeptide to be mimicked is ARG-PHE, then R₁=—(CH₂)₃—NH—C—(NH₂)₂+ and R₂=—CH₂—C₆H₃. The pseudopeptides are not limited to side groups found in the twenty genetically encoded amino acids.

-   -   a) ψ1(X₁,X₂,R₁,R₂) shows two α carbons joined by a trans         ethylene moiety,         -   X₁ and X₂ may independently be any group consistent with the             stability of the vinyl group; for example, X₁ and X₂ may be             picked from the set comprising             -   {H, -alkyl (methyl, ethyl, etc.), —O-alkyl (especially                 methyl); —O-fluoroalkyl (—O—CF₃, —O—CF₂—F₃), halo (F,                 Cl, and Br), -fluoroalkyl (e.g. —CF₃, —CF₂—CH₃, —C₂F₃),                 and secondary amine (such as N,N dimethyl)};         -   preferred X₁ groups are electronegative such as —O-alkyl and             F or hydrogen;         -   preferred X₂ groups are H, alkyl, and secondary amines,     -   b) “ψ2(X₁,X₂,X₃,X₄,R₁,R₂)” shows two α carbons joined by a         ketomethylene moiety,         -   X₁ and X₂ may independently be any group consistent with the             stability of the ketomethylene group; for example, X₁ and X₂             may be picked from the set comprising one of             -   {H, alkyl, amino, alkyl amino, —OH, —O-alkyl, —NH—COH,                 and F};         -   preferred X₁ and X₂ groups are H, methyl, —NH₂, —OH, and F             (α fluoroketones are not nearly so reactive as are chloro             and bromo ketones);         -   X₃ and X₄ may independently by any one of             -   {H and alkyl (especially methyl)};         -   H is preferred, but alkyl groups may be used to limit the             flexibility of the peptide chain,     -   c) “ψ3(X₁,X₂,X₃,X₄,X₅,X₆,R₁,R₂)” shows two α carbons joined by         two methylene groups,         -   X₁, X₂, X₃, and X₄ may independently be any group consistent             with the stability of the bismethylene group; for example,             X₁, X₂, X₃, and X₄ may be picked from the set comprising             -   {H, —O-alkyl (especially methyl), F, Cl, Br, -alkyl                 (methyl, ethyl, etc.), hydroxy, amino, alkyl hydroxy                 (e.g. —CH₂—OH, —CH(CH₃)OH), alkyl amino, and secondary                 amino (such as N,N dimethyl)};         -   X₅ and X₆ may be independently picked from the set             comprising             -   {H, alkyl, arylalkyl (e.g. —CH₂—C₆H₅), alkyl hydroxy,                 alkyl amino, aryl, alkylaryl (e.g. p-C₆H₄—CH₂—CH₃)}.     -   d) “ψ4(X₁,X₂,X₃,X₄,R₁,R₂)” shows two a carbons joined by         —CO—C(X₁)(X₂)—NH—,         -   X₁ and X₂ may independently be any group consistent with the             stability of the aminomethylketo group; for example, X₁ and             X₂ may be picked from the set comprising             -   {H, alkyl, amino, alkyl amino, —OH (but not two                 hydroxyls), —O-alkyl, and F},         -   alternatively, X₁ and X₂ can be combined as the oxygen atom             of an α keto carboxylic acid group (that is, the first             residue is a β amino keto acid);         -   X₃ and X₄ may be independently picked from the set             comprising             -   {H, alkyl, alkyl hydroxy, alkyl amino, aryl, alkylaryl                 (e.g. —CH₂—C₆H₅)}, hydrogen is preferred, but larger                 groups may be used to limit the flexibility and                 reactivity of the peptide main chain.     -   e) “ψ5(X₁,X₂,X₃,X₄,X₅,R₁,R₂)” shows two a carbons joined by a         methylene-amine group;         -   X₁ and X₂ may be any group consistent with stability of the             amine group;         -   preferably, X₁ and X₂ may be picked independently from the             set             -   {H, alkyl (methyl, ethyl, n-propyl, isopropyl, up to                 about C₆), —OH (but X₁ and X₂ can not both                 simultaneously be —OH), —O-alkyl (methyl, ethyl,                 n-propyl, isopropyl, up to about C₆)},         -   X₃ can be any group consistent with being a stable             substituent on a tertiary or secondary amine, preferably X₃             is picked from the set             -   {H, alkyl (C₁ up to about C₆), alkylhydroxy (—CH₂—OH,                 —CH₂—CH₂—OH, up to about —C₆O₂H₁₃)};         -   X₄ and X₅ may be independently picked from the set             comprising             -   {H, alkyl, alkyl hydroxy, alkyl amino, aryl, alkylaryl                 (e.g. —CH₂—C₆H₅)}, hydrogen is preferred, but other                 groups may be used to limit the flexibility and                 reactivity of The peptide main chain.     -   f) “ψ6(X₁,X₂,X₃,X₄,R₁,R₂)” shows two a carbons joined by a         vinylketone group;         -   X₁ and X₂ may be any group consistent with stability of the             compound;         -   preferably, X₁ and X₂ may be picked independently from the             set             -   {H, alkyl (methyl, ethyl, n-propyl, isopropyl, up to                 about C₆), —O-alkyl (methyl, ethyl, n-propyl, isopropyl,                 up to about C₆), alkylhydroxy (—CH₂—OH, —CH₂—CH₂—OH, up                 to about —C₆O₂H₁₃)},         -   X₃ and X₄ may be independently picked from the set             comprising             -   {H, alkyl, alkyl hydroxy, alkyl amino, aryl, alkylaryl                 (e.g. —CH₂—C₆H₅)}, hydrogen is preferred, but other                 groups may be used to limit the flexibility and                 reactivity of the peptide main chain.

FIG. 2 shows six additional pseudopeptide linkages:

-   -   a) “ψ7(X₁,X₂,R₁,R₂)”, a bisketone;         -   X₁ and X₂ may be independently picked from the set             comprising             -   {H, alkyl, alkyl hydroxy, allylamino, aryl, alkylaryl                 (e.g. —CH₂—C₆H₅)}, hydrogen is preferred, but other                 groups may be used to limit the flexibility and                 reactivity of the peptide main chain.     -   b) “ψ8(X₁,X₂,X₃,X₄,X₅,R₁,R₂)”, a cyclohexenone derivative:         -   X₁ can be any of             -   {H, —O-alkyl (especially methyl), F, -alkyl (methyl,                 ethyl, etc.), and secondary amine (such as N,N                 dimethyl)};         -   X₂, X₃, X₄, and X₅ may be picked independently from the set             -   {H, —OH (but not two hydroxyls on the same carbon),                 alkyl (methyl, ethyl, n-propyl, isopropyl, up to about                 C₆), —O-alkyl, —O-alkylaryl (e.g. —O—CH₂—C₆H₅),                 alkylhydroxy (—CH₂—OH, —CH₂—CH₂—OH, etc.), F, Cl, Br, I,                 aryl, arylalkyl, —S-alkyl} (X₄ and X₅ should not be Cl,                 Br, or I).     -   c) “ψ9(X₁,X₂,X₃,X₄,X₅,X₆,R₁,R₂)”, a cyclohexone derivative:         -   X₁, X₂, X₃, X₄, X₅, and X₆ can independently be any of             -   {H, hydroxy (but not two hydroxyl groups on one carbon),                 —O-alkyl (especially methyl), F, -alkyl (methyl, ethyl,                 etc.), and secondary amine (such as N,N dimethyl)}     -   d) “ψ10(X₁,X₂,X₃,X₄,X₅,R₁,R₂)”, a β amino acid derivative:         -   X₁ and X₅ may be independently picked from the set             comprising             -   {H, alkyl, alkyl hydroxy, alkyl amino, aryl, alkylaryl                 (e.g. —CH₂—C₆H₅)}; H is preferred.         -   X₂ and X₃ can independently be picked from the set:             -   {H, methyl, ethyl, n-propyl, isopropyl, n-butyl,                 isobutyl, s-butyl, t-butyl, other alkyls up to C₆, —OH,                 —O-methyl, —CH₂—OH}; alternatively, X₂ and X₃ can be a                 single double-bonded group, such as ═O, ═N-alkyl, or                 ═C(X₆)(X₇) (where X₆ and X₇ may be H or methyl)},         -   X₄ can be             -   {H, alkyl, aryl, or substituted hydrocarbon chains}.     -   e) “ψ11(X₁,X₂,X₃,R₁,R₂)”, an imine derivative:         -   X₁ can be any group consistent with the imine bond:             -   {H, methyl, alkyl(up to C₆), —O-methyl, —O-ethyl},         -   X₂ and X₃ may be independently picked from the set             comprising             -   {H, alkyl, alkyl hydroxy, alkyl amino, aryl, alkylaryl                 (e.g., —CH₂—C₆H₅)}.     -   f) “ψ12(X₁,X₂,X₃,X₄,R₁,R₂)”, an ether derivative:         -   X₁ and X₄ may be independently picked from the set             comprising             -   {H, alkyl, alkyl hydroxy, alkyl amino, aryl, alkylaryl                 (e.g. —CH₂—C₆H₃)}.         -   X₂ and X₃ may be picked independently from the set             -   {H, —OH (but not two hydroxyls on the same carbon),                 alkyl (methyl, ethyl, n-propyl, isopropyl, up to about                 C₆), —O-alkyl, —O-alkylaryl (e.g. —O—CH₂—C₆H₅),                 alkylhydroxy (—CH₂—OH, —CH₂—CH₂—OH, etc.), F, Cl, Br, I,                 aryl, arylalkyl, —S-alkyl}.

FIG. 3 shows a number of amino acids that can be used to create cyclic peptides by joining the side groups:

-   -   (A) shows L-2-(6-aminomethylnaphthyl)alanine,     -   (B) shows L-2-(6-carboxymethylnaphthypalanine,     -   (C) shows the crosslink generated by joining         L-2-(6-aminomethylnaphthyl)alanine to         L-2-(6-carboxymethylnaphthyl)alanine by a peptide bond between         the substituents on the 8 positions (the 6 position of         naphthylene),     -   (D) shows L-4-(2-(6-aminomethylnaphthyl))-2-aminobutyric acid,     -   (E) shows L-4-(2-(6-carboxymethylnaphthyl))-2-aminobutyric acid,         and     -   (F) shows the crosslink generated by joining (D) to (E) through         the substituents on the 6 position of each naphthene group.

FIG. 4 shows additional compounds that can be used to close a cyclic peptide:

-   -   (A) shows L-2-(4-oxymethyl-6-aminomethylnaphthyl)alanine,     -   (B) shows         L-2-(6-carboxymethyl-7-hydroxy-5,6,7,8-tetrahydronaphthyl)alanine,     -   (C) shows         L-4-(2-(6-carboxy-1,2,3,4-tetrahydronaphthyl))-2-aminobutyric         acid,     -   (D) shows 2,6 biscarboxymethylnaphthylene,     -   (E) shows 2,6 bisaminomethylnaphthylene, the separation between         nitrogens is about 8.5 Å.

FIG. 5 shows intermediates leading to an ethylene pseudopeptide and a ornithine=alanine pseudopeptide.

FIG. 6 shows compounds 4.1 and 4.2 according to formula 4. Cmpd 4.1 has a linker comprising —CH₂—(O—CH₂—CH₂)₃—CH₂—; the pseudopeptide is a fluoroethylene group. Cmpd 4.2 has a linker derived from trans cyclohexanedimethanol and ethyleneglycol units and a ketomethylene group as pseudopeptide.

FIG. 7 shows compounds 4.3 and 4.4 according to formula 4. Cmpd 4.3 has a 1,1-difluoroethane group as pseudopeptide and a linker comprising a 2,5 dialkyl benzoic acid linker. Cmpd 4.4 has an imino group as pseudopeptide and a peptide linker Gly-Pro-Thr-Val-Thr-Thr-Gly (SEQ ID NO:30).

FIG. 8 shows compounds 4.6 (in which the linker contains a p-phenyl group and a carboxylic acid side group) and 4.7 (in which the linker comprises GLY-PRO-GLY-GLU-CYS-NH₂) (SEQ ID NO:32) according to formula 4.

FIGS. 9A and 9B shows a hypotheitcal plasma kallikrein inhibitor. Panel B shows a precursor comprising H-HIS-CYS-LYS-ALA-ASN-HIS-glutamylaldehyde (SEQ ID NO:33): 1-(4-bromo-n-butane). Panel A shows the compound formed by reciprocal coupling of the butane moiety to the thiol of a second molecule of the compound in panel B.

FIG. 10A-D shows molecules useful for cyclizing a peptide.

-   -   A) shows a diacylaminoepindolidione (KEMP88b), the “exterior”         nitrogens are separated by about 13 Å,     -   B) shows diaminoepindolidione joined to a peptide through the         side groups of two GLU residues,     -   C) shows carboxymethylaminoaminoepindolidione,     -   D) shows carboxymethylaminoaminoepindolidione joined to the ends         of a peptide to form a loop.

FIG. 11A-H shows amino acids that favor a reverse turn,

-   -   A) 2-carboxy-8-aminomethylnaphthylene,     -   B) 2-carboxy-8-amino-5,6,7,8-tetrahydronaphthylene,     -   C) 1-carboxy-2-aminocyclopentane,     -   D) tetrahydroisoquinolin carboxylic acid (TIC)     -   E) 2-carboxy-7-aminoindan,     -   F) 2-carboxy-8-amino-7,8-dihydroxynaphthylene,     -   G)         2,5,7-trisubstituted-2(S)-5-H-6-oxo-2,3,4,4a,7,7a-hexahydropyrano[2,3-b]pyrrole         (CURR93), and     -   H) 4-(2-aminoethyl)-6-dibenzofuranpropionic acid (DIAZ93).

FIG. 12A-D shows compounds that force a reverse turn in a peptide chain:

-   -   A) 4-(2-aminomethyl-6-dibenzofuranethanoic acid,     -   B) 8-aminomethyl-5,6,7,8-tetrahydro-2-naphthoic acid,     -   C) Compound attributed to Freidinger et al. (FREI82) in NAGA93,     -   D) Compound attributed to Nagai and Sato (NAGA85) in NAGA93.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A large number of proteins act as serine protease inhibitors by serving as a highly specific, limited proteolysis substrate for their target enzymes. In many cases, the reactive site peptide bond (“scissile bond”) is encompassed in at least one disulfide loop, which insures that during conversion of virgin to modified inhibitor the two peptide chains cannot dissociate.

A special nomenclature has evolved for describing the active site of the inhibitor. Starting at the residue on the amino side of the scissile bond, and moving away from the bond, residues are named P1, P2, P3, etc. (SCHE67). Residues that follow the scissile bond are called P1′, P2′, P3′, etc. It has been found that the main chain of protein inhibitors having very different overall structure are highly similar in the region between P3 and P3′ with especially, high similarity for P2, P₁ and P1′ (LASK80 and works cited therein). It is generally accepted that each serine protease has sites S1, S2, etc. that receive the side groups of residues P1, P2, etc. of the substrate or inhibitor and sites S1′, S2′, etc. that receive the side groups of P1′, P2′, etc. of the substrate or inhibitor (SCHE67). It is the interactions between the S sites and the P side groups that give the protease specificity With respect to substrates and the inhibitors specificity with respect to proteases.

The serine protease inhibitors have been grouped into families according to both sequence similarity and the topological relationship of their active site and disulfide loops. The families include the bovine pancreatic trypsin inhibitor (Kunitz), pancreatic secretory trypsin inhibitor (Kazal), the Bowman-Birk inhibitor, and soybean trypsin inhibitor (Kunitz) families. (In this application, the term “Kunitz” will be used to refer to the BPTI family and not the STI family.) Some inhibitors have several reactive sites on a single polypeptide chain, and these distinct domains may have different sequences, specificities, and even topologies. One of the more unusual characteristics of these inhibitors is their ability to retain some form of inhibitory activity even after replacement of the P1 residue. It has further been found that substituting amino acids in the P₅ to P₅′ region, and more particularly the P3 to P3′ region, can greatly influence the specificity of an inhibitor. LASK80 suggested that among the BPTI (Kunitz) family, inhibitors with P1 Lys and Arg tend to inhibit trypsin, those with P1=Tyr, Phe, Trp, Leu and Met tend to inhibit chymotrypsin, and those with P1=Ala or Ser are likely to inhibit elastase. Among the Kazal inhibitors, they continue, inhibitors with P1=Leu or Met are strong inhibitors of elastase, and in the Bowman-Kirk family elastase is inhibited with P1 Ala, but not with P1 Leu.

All naturally occurring Kunitz Domain proteins have three disulfide bonds, which are topologically related so that the bonds are a-f, b-d, and c-e (“a” through “f” denoting the order of their positions along the chain, with “a” being closest to the amino-terminal), and the binding site surrounding or adjoining site “b”. The term “Kunitz domain protein” is defined, for purposes of the present invention, as being a protease inhibitor which has this fundamental disulfide bond/binding site topology, with the proviso that one of the disulfide bonds characteristic of the naturally occurring protein can be omitted.

Aprotinin-like Kunitz domains (KuDom) are structures of about 58 (typically about 56-60) amino acids having three disulfides: C5-C55, C14-C38, and C30-C51. KuDoms may have insertions and deletions of one or two residues. All naturally occurring KuDoms have all three disulfides. Engineered domains having only two have been made and are stable, though less stable than those having three. All naturally occurring KuDoms have F₃₃ and G₃₇. In addition, most KuDoms have (with residues numbered to align with BPTI) G₁₂, (F, Y, or W) at 21, Y or F at 22, Y or F at 23, Y or W at 35, G or S at 36, G or A at 40, N or G at 43, F or Y at 45, and T or S it 47.

The archetypal KuDom, bovine pancreatic trypsin inhibitor (BPTI, a.k.a. aprotonin), is a 58 a.a. serine proteinase inhibitor. Under the tradename TRASYLOL, it is used for countering the effects of trypsin released during pancreatitis. Not only is its 58 amino acid sequence known, the 3D structure of BPTI has been determined at high resolution by X-ray diffraction, neutron diffraction and by NMR. One of the X-ray structures is deposited in the Brookhaven Protein Data Bank as “6PTI” [sic]. The 3D structure of various BPTI homologues (EIGE90, HYNE90) are also known. At least sixty homologues have been reported; the sequences of 59 proteins of this family are given in Table 13 of Ladner, U.S. Pat. No. 5,233,409 and the amino acid types appearing at each position are compiled in Table 15 thereof. The known human homologues include domains of Lipoprotein Associated Coagulation Inhibitor (LACI) (WUNT88, GIRA89), Inter-α-Trypsin Inhibitor and the Alzheimer beta-Amyloid Precursor Protein (APP-I). Circularized BPTI and circularly permuted BPTI have binding properties similar to BPTI. Some proteins homologous to BPTI have more or fewer residues at either terminus. Kunitz domains are seen both as unitary proteins (e.g., BPTI) and as independently folding domains of larger proteins.

LACI is a human phosphoglycoprotein inhibitor with a molecular weight of 39 kDa. It includes three Kunitz domains.

The cDNA sequence of LACI (SEQ ID NO:25) was determined by Wun et al., J. Biol. Chem. 263 6001-6004 (1988). Mutational studies have been undertaken by Girard et al., Nature 338 518-520 (1989), in which the putative P1 residues of each of the three kunitz domains contained in the whole LACI molecule were altered from Lys36 to Ile, Arg107 to Leu; and Arg199 to Leu respectively. It has been proposed that kunitz domain 2 is required for efficient binding and inhibition of Factor Xa, while domains 1 and 2 are required for inhibition of Factor VIIa/Tissue Factor activity. The function of LACI kunitz domain 3 is as yet uncertain.

In a preferred embodiment, the KuDom of the present invention is substantially homologous with the first Kunitz Domain (K₁) of LACI residues 50-107 of SEQ ID NO:25), with the exception of the kallikrein-binding related modifications discussed hereafter. For prophylaxis or treatment of humans, since BPTI is a bovine protein and LACI is a human protein, the mutants of the present invention are preferably more similar in amino acid sequence to LACI (K1) (residues 50-107 of SEQ ID NO:25) than to BPTI, to reduce the risk of causing an adverse immune response upon repeated administration.

The amino acid sequence of these mutant LACI domains has been numbered, for present purposes, to align them with the amino acid sequence of mature BPTI, in which the first cysteine is at residue 5 and the last at residue 55.

Most naturally occurring Kunitz domains have disulfides between 5:55, 14:38, and 30:51. Drosophila funebris male accessory gland protease inhibitor (GeneBank accession number P11424) has no cysteine at position 5, but has a cysteine at position −1 (just before typical position 1); presumably this forms a disulfide to CYS⁵⁵. Engineered Kunitz domains have been made in which one or another of the disulfides have been changed to a pair of other residues (mostly ALA). Proteins having only two disulfides are less stable than those with three.

“Variegation” is semirandom mutagenesis of a binding protein. It gives rise to a library of different but structurally related potential binding proteins. The residues affected (“variable residues”) are predetermined, and, in a given round of variegation, are fewer than all of the residues of the protein. At each variable residue position, the allowable “substitution set” is also predetermined, independently, for each variable residue. It may be anywhere from 2 to 20 different amino acids, which usually, but need not, include the “wild type” amino acid for that position. Finally, the relative probabilities with which the different amino acids of the substitution set are expected (based on the synthetic strategy) to occur at the position are predetermined.

Variegation of a protein is typically achieved by preparing a correspondingly variegated mixture of DNA (with variable codons encoding variable residues), cloning it into suitable vectors, and expressing the DNA in suitable host cells.

For any given protein molecule of the library, the choice of amino acid at each variable residue, subject to the above constraints, is random, the result of the happenstance of which DNA expressed that protein molecule.

Applicants have screened a large library of LACI (K1) mutants, with the following results:

BPTI # (Lac I) Library Residues Preferred Residues 13 P LHPR HP 16 A AG AG 17 I FYLHINA NSA SCPRTVDG 18 M all HL 19 K LWQMKAG QLP SPRTVE 31 E EQ E 32 E EQ EQ 34 I all STI 39 E all GEA

In the table above, “library residues” are those permitted to occur, randomly, at that position, in the library, and “preferred residues” are those appearing at that position in at least one of the 10 variants identified as binding to human kallikrein.

At residues 13, 16, 17, 18, 31, and 32, the selections are very strong. At position 34, the selection for either SER or THR is quite strong. At position 39, the selection for GLY is strong. Position 19 seems to be rather tolerant.

The amino acid residues of the binding proteins of the present invention may be, characterized as follows (note that the residues are numbered to correspond to BPTI):

-   -   (a) the residues involved in disulfide bond formation (C5-C55,         C14-C38, and C30-C51);     -   (b) the residues subjected to variation in the library (13, 16,         17, 18, 19, 31, 32, 34, 39); and     -   (c) the remaining residues.

At a minimum, the Kunitz domain proteins of the present invention must contain at least two disulfide bonds, at the same (or nearly the same) positions as in LACI(K1)(residues 50-107 of SEQ ID NO:25). The C5-C55 disulfide is the most important, then the C30-C51, and lastly the C14-C38. If a Cys is replaced, it is preferably a conservative non-proline substitution with Ala, and Thr especially preferred. Preferably, three disulfide bonds are formed, at the same, or nearly the same, positions as in LACI(K1)(residues 50-107 of SEQ ID NO:25). By “nearly the same”, we mean that as a result of a double mutation, the location of a Cys could be shifted by one or two positions along the chain, e.g., Cys30 Gly/Glx31 Cys.

With regard to the variable residues of the library, it should be appreciated that Applicants have not necessarily sequenced all of the positive mutants in the library, that some of the possible mutant proteins may not actually have been present in the library in detectable amounts, and that, at some positions, only some of the possible amino acids were intended to be included in the library. Therefore, the proteins of the present invention, may, at the aforementioned positions (13, 16-19, 31, 32, 34, 39) in decreasing order of preference, exhibit:

-   -   (a) the residues specifically identified as preferred;     -   (b) conservative (or semi-conservative) substitutions for the         residues of (a) above, which were not listed as “library         residues”;     -   (c) nonconservative substitutions for the residues of (a) above,         which were not listed as library residues;     -   (d) conservative substitutions for the residues of (a) above,         which were listed as library residues

In addition, for the protein to be substantially homologous with LACI(K1)(residues 50-107 of SEQ ID NO:25), residue 12 must be Gly, residue 23 must be aromatic, residue 33 must be aromatic, residue 37 must be Gly, (if the 14-28 disulfide bond is preserved, but otherwise is not restricted), and residue 45 must be aromatic.

With regard to the remaining residues, these may be, in decreasing order of preference:

-   -   (a) the wild-type amino acid found at that position in LACI         (K1)(residues 50-107 of SEQ ID NO:25);     -   (b) conservative substitutions for (a) above which are also         found at that position in one or more of the homologues of BPTI,         or in BPTI itself (SEQ ID NO:1), as listed in Table 15 of the         '409 patent;     -   (c) conservative substitutions for (a) above which are not         listed at that position in Table 15 of the '409 patent;     -   (d) other amino acids listed at that position in Table 15 of the         ‘409 patent’     -   (e) conservative substitutions for the amino acids of (a) above,         not already included in (a)-(c);     -   (f) any other residues, with non-proline residues being         preferred.

Additional variegation could give rise to proteins having higher affinity for pKA. The intention is to make a new first loop (residues 10-21) including what we got in the first variation. Table 202 shows variegation for residues 10-21. Above the DNA sequence, underscored AAs are from the selected kallikrein binders while bold AAs are those found in LACI-K1 (residues 50-107 of SEQ ID NO:25). We allow D, E, N, or K at 10 (underscored amino acids have been seen on Kunitz domains at position 10). We allow 8 AAs at 11: {N, S, I, T, A, G, D, V}. Previous variegation had allowed {P,L,H,R} at 13. We selected H very strongly; LACI-K1 (residues 50-107 of SEQ ID NO:25) has P at 13 and no reported Kunitz domain has HIS at 13. In one case, PRO was selected at 13. Judging that PRO₁₃ is not optimal, we now allow {E, K, D, Y, Q, H, N}. At 15, we allow K or R. Enzymes that cut after basic residues (K or R) can show two fold tighter binding when the preferred basic residues is available. Which is preferred for a given enzyme may well depend on the other residues in the inhibitor; we will allow both. At 16, we add V or D to the group {A,G} previously allowed. LACI-K1 (residues 50-107 of SEQ ID NO:25) has a hydrophobic residue at 17, but we selected N strongly with S allowed (both are hydrophilic). Thus, we allow either N or S. At 18, we selected HIS strongly with LEU being allowed. We now allow either HIS or LEU. At 19, we allow eleven amino acids: {A, T, P, H, N, Y, Q, K, D, E}. HIS, TYR, ASN, and ASP were not allowed in the first variegation. This variegation allows 131,072 DNA sequences and 78,848 amino acid sequences; 99.92% of the amino-acid sequences are new. One preferred procedure is to ligate DNA that embodies this variegation into DNA obtained from selection after the initial variegation at residues 31, 32, 34, and 39. Thus a small population of sequences at these locations is combined with the new variegation to produce a population of perhaps 10⁷ different sequences. These are then selected for binding to human pKA.

A second variegation, shown in Table 204; allows changes at residues 31, 32, 34, 39, 40, 41, and 42. In the first selection, we saw strong selection at positions 31 and 32 and weaker selection at positions 34 and 39. Thus, we now allow more variability at 31 and 32, less variability at 34 and 39, and binary variability at 40, 41, and 42. This variegation allows 131,072 DNA sequences and 70,304 amino-acid sequences. The fraction of amino-acid sequences that are new is 0.997.

The tem “substantially homologous”, when used in connection with amino acid sequences, refers to sequences which are substantially identical to or similar in sequence, giving rise to a homology in conformation and thus to similar biological activity. The term is not intended to imply a common evolution of the sequences.

Typically, “substantially homologous” sequences are at least 50%, more preferably at least 80%, identical in sequence, at least over any regions known to be involved in the desired activity. Most preferably, no more than five residues, other than at the termini, are different. Preferably, the divergence in sequence, at least in the aforementioned regions, is in the form of “conservative modifications”.

“Conservative modifications” are defined as

-   -   (a) conservative substitutions of amino acids as hereafter         defined; and     -   (b) single or multiple insertions or deletions of amino acids at         the termini, at interdomain boundaries, in loops or in other         segments of relatively high mobility (as indicated, e.g., by the         failure to clearly resolve their structure upon X-ray         diffraction analysis or NMR).     -   Preferably, except at the termini, no more than about five amino         acids are inserted or deleted at a particular locus, and the         modifications are outside regions known to contain binding sites         important to activity.

Conservative substitutions are herein defined as exchanges within one of the following five groups:

-   -   I. Small aliphatic, nonpolar or slightly polar residues:         -   Ala, Ser, Thr (Pro, Gly)     -   II. Polar, negatively charged residues: and their amides         -   Asp, Asn, Glu, Gln     -   III. Polar, positively charged residues:         -   His, Arg, Lys     -   IV. Large, aliphatic, nonpolar residues:         -   Met, Leu, Ile, Val (Cys)     -   V. Large, aromatic residues:         -   Phe, Tyr, Trp

Residues Pro, Gly and Cys are parenthesized because they have special conformational roles. Cys participates in formation of disulfide bonds. Gly imparts flexibility to the chain. Pro imparts rigidity to the chain and disrupts a helices. These residues may be essential in certain regions of the polypeptide, but substitutable elsewhere.

Semi-conservative substitutions are defined to be exchanges between two of groups (I)-(V) above which are limited to supergroup (a), comprising (I), (II) and (III) above, or to supergroup (B), comprising (IV) and (V) above.

Two regulatory DNA sequences (e.g., promoters) are “substantially homologous” if they have substantially the same regulatory effect as a result of a substantial identity in nucleotide sequence. Typically, “substantially homologous” sequences are at least 50%, more preferably at least 80%, identical, at least in regions known to be involved in the desired regulation. Most preferably, no more than five bases are different.

The Kunitz domains are quite small; if this should cause a pharmacological problem, such as excessively quick elimination from the circulation, two or more such domains may be joined by a linker. This linker is preferably a sequence of one or more amino acids. A preferred linker is one found between repeated domains of a human protein, especially the linkers found in human BPTI homologues, one of which has two domains (BALD85, ALBR83b) and another of which three (WUNT88). Peptide linkers have the advantage that the entire protein may then be expressed by recombinant DNA techniques. It is also possible to use a nonpeptidyl linker, such as one of those commonly used to form immunogenic conjugates. For example, a BPTI-like KuDom to polyethyleneglycol, so called PEGylation (DAVI79).

Certain plasma kallikrein-inhibiting Kunitz domains are shown in Table 103. The residues that are probably most important in binding to plasma kallikrein are H₁₃, C₁₄, K₁₅, A₁₆, N₁₇, H₁₈, Q₁₉, E₃₁, E₃₂, and X₃₄ (where X is SER or THR). A molecule that presents the side groups of N₁₇, H₁₈, and Q₁₉ plus any two of the residues H₁₃, C₁₄, K₁₅, (or R₁₅), E₃₁, E₃₂, and X₃₄ (X=SER or THR) in the corresponding orientation is likely to show strong, specific binding for plasma kallikrein. A basic residue at 15 is NOT thought to be essential.

The compounds are not limited to the side groups found in genetically encoded amino acids; rather, conservative substitutions are allowed. LYS₁₅ can be replaced by ARG, ornithine, guanidolysine, and other side groups that carry a positive charge. ASN₁₇ can be replaced by other small, neutral, hydrophilic groups, such as (but without limitation) SER, O-methyl serine, GLN, α-amidoglycine, ALA, α-aminobutyric acid, and α-amino-γ-hydroxybutyric acid (homoserine). HIS₁₈ could be replaced with other amino acids having one or more of the properties: amphoteric, aromatic, hydrophobic, and cyclic. For example (without limitation), HIS₁₈ could be replaced with L-C^(δ)methylhistidine, L-C^(ε)methylhistidine, L-p-aminophenylalanine, L-m-(N,N-dimethylamino)phenylalanine, canavanine (Merck Index 1745), and N-methylasparagine.

A molecule that presents side groups corresponding to, for example, K₁₅, N₁₇, H₁₈, and E₃₂ might bind to plasma kallikrein in a way that blocks access of Macromolecules to the catalytic site, even though the catalytic site is accessible to small molecules. Thus, in testing possible inhibitors, it is preferred that they be tested against macromolecular substrates.

Ways to Improve Specificity of, for example, KKII/3#7 for Plasma Kallikrein:

Note that K₁₅ or (R₁₅) may not be essential for specific binding although it may be used. Not having a basic residue at the P1 position may give rise to greater specificity. The variant KKII/3#7-K15A (SEQ ID NO:31; shown in Table 1017), having an ALA at P1, is likely to be a good plasma kallikrein inhibitor and may have higher specificity for plasma kallikrein relative to other proteases than does NS4. The affinity of KKII/3#7-K15A (SEQ ID NO:31) for plasma kallikrein may be less than the affinity of KKII/3#7 (SEQ ID NO:8) for plasma kallikrein, but in many applications, specificity is more important.

Smaller Domains that Bind Plasma Kallikrein:

Kunitz domains contain 58 amino acids (typically). It is possible to design smaller domains that would have specific binding for plasma kallikrein. Table 50 shows places in BPTI where side groups are arranged in such a way that a disulfide is likely to form if the existing side groups are changed to cysteine. Table 55 shows some “cut-down” domains that are expected to bind and inhibit plasma kallikrein.

The first shortened molecule (ShpKa#1, SEQ ID NO:17) is derived from BPTI and comprises residues 13-39. The mutations P13H, R17N, I18H, I19Q, Q31E, T32E, V34S, and R39G are introduced to increase specific binding to plasma kallikrein. The mutation Y21C is introduced on the expectation that a disulfide will form between CYS₂₁ and CYS₃₀. It is also expected that a disulfide will form between CYS₁₄ and CYS₃₈ as in BPTI. These disulfides will cause the residues 13-19 and 31-39 to spend most of their time in a conformation highly similar to that found for the corresponding residues of BPTI. This, in turn, will cause the domain to have a high affinity for plasma kallikrein.

The second shortened molecule (ShpKa#2, SEQ ID NO:18) is also derived from BPTI and comprises residues 13-52. The mutations P13H, R17N, I18H, I19Q, Q31E, T32E, V34T, and R39G are introduced to increase specific binding to plasma kallikrein. Because residues 13-52 are included, the two natural disulfides 14:38 and 30:51 can form.

A third shortened BPTI derivative (ShpKa#3, SEQ ID NO:19) is similar to ShpKa#2 (SEQ ID NO:18) but has the mutations P13H, K15R, R17N, I18H, I19Q, R20C, Q31E, T32E, V34S, Y35C, and R39G. The residues 20 and 35 are close enough in BPTI that a disulfide could form when both are converted to cysteine. At position 34, both ASP and GLY seen to give good plasma kallikrein binders. As we are introducing a new disulfide bond between 35 and 20, it seems appropriate to allow extra flexibility at 34 by using SER.

The fourth shortened molecule (ShpKa#4, SEQ ID NO:20) is derived from the LAC1-K1 derivative KKII/3#7 (residues 13-39 OF SEQ ID NO:8) and carries only the mutation F21C. It is likely that a disulfide will form between CYS₂₁ and CYS₃₀.

ShpKa#5 (SEQ ID NO:21) is related to ShpKa#4 (SEQ ID NO:20) by replacing residues ILE₂₅-PHE₂₆ with a single GLY. The α carbons of residues 24 and 27 are separated by 5.5 Å and this gap can be bridged by a single GLY.

ShpKa#6 (SEQ ID NO:22) is related to ShpKa#4 (SEQ ID NO:20) by the additional mutations R20C and Y35C. These residues are close in space so that a third disulfide might form between these residues.

ShpKa#7 (SEQ ID NO:23) is related to ShpKa#6 (SEQ ID NO:22) by the mutations N24D, I25V, F26T, and T27E. The subsequence D₂₄VTE is found in several Kunitz Domains and reduces the positive charge on the molecule.

ShpKa#8 (SEQ ID NO:24) is related to ShpKa#6 (SEQ ID NO:22) by the mutations I25P, F26D, and T27A. The subsequence P₂₅DA is found in the KuDom of D. funebris. This has the advantage of inserting a proline and reducing net positive charge. It is not known that reduced positive charge will result in greater affinity or specificity. The ability to change the charge at a site far from the binding site is an advantage.

Non-Kunitz Domain Inhibitors of Plasma Kallikrein Derived from the LACI-K1 Plasma Kallikrein Inhibitors

The Kunitz domain binding proteins of the present invention can be used as structural probes of human plasma kallikrein so that smaller protein, small peptidyl, and non-peptidyl drugs may be designed to have high specificity for plasma kallikrein.

The non-Kunitz domain inhibitors of the present invention can be divided into several groups:

-   -   1) peptides of four to nine residues,     -   2) cyclic peptides of five to twenty-five residues,         -   a) those closed by disulfides,         -   b) those closed by main-chain peptide bonds,         -   c) those closed by bonds (other than disulfides) between             side groups,     -   3) compounds in which one or more peptide bonds are replaced by         nonpeptidyl bonds which, nonetheless, are somewhat analogous to         peptide bonds in length, structure, etc., so-called         “pseudopeptides”, and     -   4) compounds in which the side groups corresponding to those of         a protein are supported by a framework that is not related to         peptides or pseudopeptides.

Inhibitors may belong to more than one of these groups. For example, a compound may be cyclic and have two peptide linkages replaced by “pseudopeptide” linkages, or a compound could have three side groups attached to an organic ring compound with a dipeptide group also attached.

1) Peptides of Four to Nine Residues:

One class of potential inhibitors of plasma kallikrein is peptides of four to nine residues. The peptides are not limited to those composed of the genetically-encodable twenty amino acids. Unless stated otherwise, the levo enantiomer (l- or L-) of chiral; amino acids (that is, the conformation about the a carbon is as in naturally occurring genetically-encoded amino acids) is preferred. Peptides of four to nine residues having the sequence of Formula I are likely to be specific plasma kallikrein inhibitors.

X₁—X₂—X₃—X₄—X_(s)—X₆—X₇—X₈—X₉  Formula 1

wherein:

-   -   the first residue may be any one of X₁, X₂, X₃, X₄, or X₅;     -   the last residue may be either X₈ or X₉,     -   X₁ corresponds to the P4 residue the inhibitor and may be picked         from the set comprising {any d or l amino acid (having free or         blocked amino group) or an amino group (possibly blocked with         one of the groups acetyl, formyl, methyl, ethyl, propyl,         isopropyl, n-butyl, secondary butyl, tertiary butyl, benzyl, or         similar group)}; preferred choices are hydrogen, acetyl,         glycine, and formyl,     -   X₂ corresponds to the P3 residue and is most preferably l-HIS;         alternatives include (without limitation)         L-C^(δ)methylhistidine, L-C^(ε)methylhistidine,         L-p-aminophenylalanine, L-m-(N,N-dimethylamino)phenylalanine,         canavanine (Merck Index 1745), and N-methylasparagine; all the         alternatives have one or more of the properties: amphoteric,         aromatic, hydrophobic, and cyclic, as does HIS,     -   X₃ corresponds to the P2 residue and may be any 1 amino acid,         preferably uncharged and hydrophobic; if X₃ is cysteine, the         sulphur is blocked by one of a) a second cysteine residue, b) a         thiol reagent, c) an alkyl group, if X₃ is not cysteine, then         PRO is a preferred choice because the φ of CYS₁₄ is in the range         accessible to PRO and the side group of PRO is not dissimilar to         the disulfide group, other preferred alternatives at X₃ include         l-MET, l-GLN, l-pipecolic acid (Merck Index 7425),         l-2-azitidinecarboxylic acid (Merck Index 923), l-LEU, l-ILE,         l-VAL, cycloleucine (Merck Index 2740), l-α-aminobutylric acid,         l-aminocyclopropane-l-carboxylic acid, and l-methoxyalanine, X₄         corresponds to P1 residue and is most preferably l-LYS, l-ARG,         l-ornithine, or l-guanidolysine (i.e.         NH₂—CH(COOH)—(CH₂)₄—NH—C—(NH₂)₂+); l-ALA, l-SER, and GLY are         preferred alternatives,     -   X₅ corresponds to the P1′ residue and is most preferably ALA if         X₄ is present; l-PRO, GLY, and l-SER are preferred alternatives;         X₅ may be any amino acid if X₁-X₄ are absent,     -   X₆ corresponds to the P2′ residue and is most preferably l-ASN,         l-SER, l-GLN; other amino acids having small, neutral,         hydrophilic groups; such as (but without limitation) O-methyl         serine, α-amidoglycine, α-aminobutyric acid, β-fluoroalanine,         N-methylasparagine, N,N-dimethylasparagine, and         α-amino-γ-hydroxybutyric acid (homoserine), are preferred         alternatives, corresponds to the P3′ residue and is most         preferably HIS; preferred alternatives include, for example and         without limitation, L-C^(δ)methylhistidine,         L-C^(ε)methylhistidine, L-p-aminophenylalanine,         L-m-(N,N-dimethylamino)phenylalanine, canavanine (Merck Index         1745), and N-methylasparagine; all the alternatives have one or         more of the properties: amphoteric, aromatic, hydrophobic, and         cyclic, as does HIS,     -   X₈ corresponds to the P4′ residue and most preferably is GLN;         other neutral residues including, for example and without         limitation, ASN, α-amino-δ-amidoadipic acid, HIS, and         α-amino-ε-amidopimelic acid. The preferred alternative all have         minimal size and no charged groups, and     -   X₉ corresponds to the p5′ residue and may be any l- or d-amino         acid, preferably or l-ALA (which occur frequently at this         position of Kunitz Domains), or GLU, ASP, or other amino acids         having acidic side groups (which might interact with plasma         kallikrein in place of GLU₃₂ or GLU₃₁), or homoserine or other         amino acid having a hydroxyl, or X₉ may be a free or blocked         carboxyl group of X₈ or X₉ may be a free or blocked amide group         of X₈; if X₅ is the first amino acid, then X₉ is present.

These compounds can be synthesized by standard solid-phase peptide synthesis (SPPS) using tBoc or Fmoc chemistry. Synthesis in solution is also allowed. There are many references to SPPS, including Synthetic Peptides, Edited by Gregory A Grant, WH Freeman and Company, New York, 1992, hereinafter GRAN92.

Examples of class 1 include:

-   1.1) +NH₂-GLY₁-HIS-PRO-LYS₄-ALA₅-ASN-HIS-GLN-LEU₉-NH₂ (SEQ ID NO:34;     9 amino acids), -   1.2) +NH₂-HIS-PRO₃-ARG₄-ALA-ASN-HIS-GLN₈-COO— (SEQ ID NO:35; 7 amino     acids), -   1.3) +NH₂-PRO₃-ARG₄-ALA-ASN-HIS₂-COOC2H5 (SEQ ID NO:36; 5 amino     acids), -   1.4) CH₃CO—NH—CH₂—CO-HIS-MET-LYS₄-ALA-ASN-HIS-GLN-GLU-COO— (SEQ ID     NO:37; X₁ is acetylglycine, 9 amino acids), -   1.5)     l-pipecolyl-l-ornithinyl₄-ALA₅-ASN-L-C^(δ)methylhistidyl-GLN-NH₂ (6     amino acids), and -   1.6)     l-2-azitidinyl-l-guanidolysyl₄-PRO-ASN-HIS-l-α-aminopimelamideyl-GLU-CONH₂     (7 amino acids).     2) Cyclic Peptides of from about 8 to about 25 Amino Acids:

A second class of likely plasma kallikrein inhibitors are cyclic peptides of from about 8 to about 25 residues in which Formula 1 is extended to allow cyclization between X₈ or X₉ and one of: 1) X₁, 2) X₂, 3) X₃, 4) X₄, 5) X₅, or 6) the side group of one of these residues. The amino acids of this class are not restricted to the twenty genetically encodable amino acids. Closure to the amino terminus of residues in cases 1-5 involves standard peptide chemistry. Leatherbarrow and Salacinski (LEAT91) report “design of a small peptide-based proteinase inhibitor by modeling the active-site region of barley chymotrypsin inhibitor 2.” This twenty-amino-acid peptide has a K_(D) for chymotrypsin of 28 pM. If the side group of X₃ contains a free thiol, as in CYS, then the peptide may be extended to include a second CYS that will form a disulfide with CYS₃. Thus, the sequences of the Formulae 2.1 through 2.12 are likely to be specific inhibitors of plasma kallikrein.

Wherein:

-   -   the first residue may be any one of X₁, X₂, or X₃,     -   X₁ corresponds to the P4 residue the inhibitor and may be picked         from the set comprising {any d or l amino acid (having free or         blocked amino group) or an amino group (possibly blocked with         one of the groups acetyl, formyl, methyl, ethyl, propyl,         isopropyl, n-butyl, secondary butyl, tertiary butyl, benzyl, or         similar group)}; preferred choices are hydrogen, acetyl,         glycine, and formyl,     -   X₂ corresponds to the P3 residue and is most preferably l-HIS;         alternatives include (without limitation)         L-C^(δ)methylhistidine, L-C^(ε)methylhistidine,         L-p-aminophenylalanine, L-m-(N,N-dimethylamino)phenylalanine,         canavanine (Merck Index 1745), and N-methylasparagine; all the         alternatives have one or more of the properties: amphoteric,         aromatic, hydrophobic, and cyclic, as does HIS,     -   X₃ corresponds to the P2 residue and may be any l amino acid,         preferably uncharged and hydrophobic; if X₃ is cysteine, the         sulphur is blocked by one of a) a second cysteine residue, b) a         thiol reagent, c) an alkyl group, if X₃ is not cysteine, then         PRO is a preferred choice because the φ of CYS₁₄ is in the range         accessible to PRO and the side group of PRO is not dissimilar to         the disulfide group, other preferred alternatives at X₃ include         l-MET, l-GLN, l-pipecolic acid (Merck Index 7425),         l-2-azitidinecarboxylic acid (Merck Index 923), l-LEU, l-ILE,         l-VAL, cycloleucine (Merch Index 2740), l-α-aminobutylric acid,         l-aminocyclopropane-l-carboxylic acid, and l-methoxyalanine,     -   X₄ corresponds to the P1 residue and is most preferably l-LYS,         l-ARG, l-ornithine, or l-guanidolysine i.e.         NH₂—CH(COOH)—(CH₂)₄—NH—C—(NH₂)₂+); l-ALA, l-SER, and GLY are         preferred alternatives,     -   X₅ corresponds to the P1′ residue and is most preferably ALA if         X₄ is present; l-PRO, GLY, and l-SER are preferred alternatives;         X₅ may be any amino acid if X₁-X₄ are absent,     -   X₆ corresponds to the P2′ residue and is most preferably l-ASN,         l-SER, l-GLN; other amino acids having small, neutral,         hydrophilic groups, such as (but without limitation) O-methyl         serine, α-amidoglycine, α-aminobutyric acid, β-fluoroalanine,         N-methylasparagine, N,N-dimethylasparagine; and         α-amino-γ-hydroxybutyric acid (homoserine), are preferred         alternatives,     -   X₇ corresponds to the P3′ residue and is most preferably HIS;         preferred alternatives include, for example and without         limitation, L-C^(δ)methylhistidine, L-C^(ε)methylhistidine,         L-p-aminophenylalanine, L-m-(N,N-dimethylamino)phenylalanine,         canavanine (Merck Index 1745), and N-methylasparagine; all the         alternatives have one or more of the properties: amphoteric,         aromatic, hydrophobic, and cyclic, as does HIS,     -   X₈ corresponds to the P4′ residue and most preferably is GLN;         other neutral residues including, for example and without         limitation, ASN, α-amino-δ-amidoadipic acid, HIS, and         α-amino-ε-amidopimelic acid. The preferred alternative all have         minimal size and no charged groups, and     -   X₉ corresponds to the p5′ residue and may be any l- or d-amino         acid, preferably l-ARG, l-LEU, or l-ALA (which occur frequently         at this position of Kunitz Domains), or GLU, ASP, or other amino         acids having acidic side groups (which might interact with         plasma kallikrein in place of GLU₃₂ or GLU₃₁), or homoserine or         other amino acid having a hydroxyl, or X₉ may be a free or         blocked carboxyl group of X₈ or X₉ may be a free or blocked         amide group of X₈; if X₅ is the first amino acid, then X₉ is         present,     -   Linkage is a collection of atoms that connect one of X₈ or X₉ to         one of X₁, X₂, or X₃. The linkage could be closed by any one or         more of disulfide bonds, peptide bonds, other covaluent bonds.         The linkage is designed to bend sharply after the recognition         sequence; sequences such as GLY-PRO, PRO-GLY, GLY-GLY, SER-GLY,         and GLY-THR which are known to favor turns are preferred after         the recognition sequence (X₄-X₈) and (for those cases in which         the loop is closed by main-chain peptide bonds) before the         lowest-numbered residue of Formula 2; the linkage could be         picked from the set comprising:     -   1) —(CH₂)n- where n is between 1 and about 18;     -   2) —CH₂—(O—CH₂—CH₂)n- where n is between 1 and about 6;     -   3) saccharides comprising one to about five hexose, pentose, or         other rings, sugars offering the advantage of favoring         solubility;     -   4) diaminoepindolidione, 2,6-diaminonaphthylene,         2,6-diaminoanthracene, and similar rigid diamines joined to the         carboxylic acid groups either at the C-terminus or in the side         groups of ASP, GLU, or other synthetic amino acids;     -   5) 2,6-dicarboxynaphthylene, 2,6-dicarboxyanthracene, and         similar rigid dicarboxylic acids joined to primary amino groups         on the peptide, such as the a amino group or the side groups of         LYS or ornithine;     -   6) one or more benzene, naphthylene, or anthracene-rings or         their heterocyclic analogues, having acidic, oxymethyl, basic,         halo, or nitro side groups and joined through alkyl or ether         linkages.

The linker should not be too hydrophobic, especially if it is flexible. A chain of methylene groups is likely to undergo “hydrophobic collapse” (Dan-Rich paper.) Ether linkages are chemically stable and avoid the tendency for the linker to collapse into a compact mass.

Some examples, without limitation, of Formula 2 are:

In Formula 2.1, X₁ is an amino group, X₂ is HIS, X₃ is CYS, X₄ is LYS, X₉ is GLU, and the linker is -THR-ILE-THR-THR-CYS-NH₂. The loop is closed by a disulfide. Table 220 contains the distances between α carbons of the residues 11 through 21 and 32, 32, and 34 in BPTI. CYS₃ in Formula 2.1 corresponds to CYS₁₄ of BPTI and GLU₉ corresponds to ARG₂₀. These residues are separated (in the desired conformation) by 14.2 Å. Thus the five residue linker can span this gap. The use of THR and ILE favors an extended conformation of the linker. GLU₉ is intended to interact with the components of plasma kallikrein that interact with GLU₃₁ and GLU₃₂ in the Kunitz-domain KKII/3#7 (SEQ ID NO:8) plasma kallikrein inhibitor.

In Formula 2.2, X₁ is an acetate group, X₃ is CYS, X₄ is ARG, X₉ is GLU, and the linker is -GLU₁₀-THR-THR-VAL-THR-GLY-CYS-NH₂. The loop is closed by a disulfide. This differs from 2.1 in having two acidic residues where the chain is likely to turn and where these acidic side groups can interact with those components of plasma kallikrein that interact with GLU₃₁ and GLU₃₂ in the Kunitz-domain KKII/3#7 (SEQ ID NO:8) plasma kallikrein inhibitor.

In Formula 2.3, X₁ is a glycine, X₂ is HIS, X₃ is CYS, X₄ is ARG, X₆ is GLN, X₉ is GLY (actually part of the linker), and the linker is -GLY₉-PRO-THR-GLY-CYS-NH₂.

In Formula 2.4, the loop is closed by a peptide bond between THR₁₄ and HIS₂. The compound may be synthesized starting at any point and then cyclized. X₃ is PRO and X₄ is ARG. The TTVT sequence favors extended structure due to the branches at the β carbons of the side groups. GLY₉ favors a turn at that point. GLU₁₀ allows interaction with those components of plasma kallikrein that interact with GLU₃₁ and GLU₃₂ of KKII/3#7 (SEQ ID NO:8). GLU₁₀ of formula 2.4 could be replaced with other amino acids having longer acidic side groups such as α-aminoadipic acid or α-aminopimelic acid.

In formulae 2.5, 2.6, and 2.7 there are two disulfides. Having two disulfides is likely to give the compound greater rigidity and increase the likelihood that the sequence from 5 to 10 is extended. Having two consecutive CYSs favors formation of disulfides to other CYSs, particularly those at the beginning of the peptide. In formula 2.5, the disulfides are shown from C₂ to C₁₇ and C₄ to C₁₈. This bonding may not be as favorable to proper conformation of residues 5 through 10 as is the bonding C₂ to C₁₇ and C₄ to C₁₆ as shown in formula 2.6. Which of these forms is probably most strongly influenced by the amino-acid sequence around the cysteines and the buffer conditions in which the molecule folds. Placing charged groups before and after the cysteines may favor the desired structure. For example, D₁C₂HC₄K₅ ANHQEGPTVD₁₅ C₁₆C₁₇K₁₈ (SEQ ID NO:45) would have D₁ close to K₁₈ and K₅ close to D₁₅ in the desired structure, but would have D₁ close to D₁5 and K₅ close to K₁₈ in the less preferred structure.

Optionally, the side group of X₃ in Formula 2 could be other than CYS but such that it can selectively form a cross-bridge to a second residue in the chain. As discussed in GRAN92 (p. 141) selective deprotection of primary amine and carboxylic acid side groups allows selective formation of intrachain crosslinks.

Formulae 2.8, 2.9, 2.10, and 2.11 show cyclic peptides which are likely to inhibit plasma kallikrein specifically in which the loop is closed by a peptide bond or bonds between the side groups of amino acids. During synthesis, the substrates for LYS₃ and GLU₁₃ (formula 2.8), GLU₃ and LYS₁₄ (formula 2.9), GLU₂ and GLU₉ (formula 2.10), and LYS₂ and LYS₁₀ (formula 2.11) are blocked differently from other reactive side groups of their respective peptides so that these side groups can be deprotected while leaving the other groups blocked. The loop is then closed and the other side groups deprotected.

The α carbons of LYS and GLU residues that are joined by a peptide bond through the side groups may be separated by up to about 8.5 Å. In BPTI (SEQ ID NO: 1), the α carbons of CYS₁₄ and ARG are separated by 8.9 Å. The second version of Formula 2.9 shows the peptide chain folded back after GLY₁₀; PRO₁₁ is approximately as far from the a carbon of residue 3 as is the α carbon of GLN₉; THR₁₂ is about as far from residue 3 as is GLN₈; and so forth, so that LYS₁₄ is about as far from residue 3 as is ARG₆, which would be about 8.9 Å if the peptide is in the correct conformation. The peptide of formula 2.8 is one amino acid shorter. The sequence differs by omission of a PRO, so the chain should be less rigid.

For formula 2.10, the loop is closed by formation of two peptide bonds between the side groups of GLU₂ and GLU₉ with 2,6 bisaminomethylnaphthylene (FIG. 4, panel E). In Formula 2.11, residues 2 and 9 are lysine and 2,6 biscarboxynaphthylene (FIG. 4, panel D) could be used. Linkers of this sort have the advantage that the linker not only bridges the gap, but that it also keeps the joined amino acids separated by at least about 8 Å. This encourages the peptide to fold into the desired extended conformation.

Loop closure by peptide bond or bonds has the advantage that it is not sensitive to reduction as are disulfides. Unnatural amino acids have different cross-linkable side groups may be used. In particular, acid side groups having more methylene groups, aryl groups, or other groups are allowed. For example, the side groups —CH₂-p-C₆H₄—COOH, -p-C₆H₄—CH₂—COOH, —(CH₂)₃—COOH, and -(transCH═CH)—CH₂—COOH could be used. Also, side groups (other than that of LYS) carrying amino groups may be used. For example, —(CH₂)₂—NH₃+, —(CH₂)₃—NH₃+, —(CH₂)₃—NH₃+, —CH₂-2-(6-aminomethylnaphthyl) (shown in FIG. 3, panel A), —CH₂-2-(6-carboxymethylnaphthyl) (shown in FIG. 3, panel B), —CH₂—CH₂-2-(6-aminomethylnaphthyl) (shown in FIG. 3, panel D), —CH₂—CH₂-2-(6-carboxymethylnaphthyl) (shown in FIG. 3, panel E), and —CH₂-p-C₆H₄—CH₂—NH₃+ are suitable.

The naphthylene derivatives shown in FIGS. 3 and 4 have the advantage that, for the distance spanned, there are relatively few rotatable bonds.

Another alternative within Formula 2 is a repeated cyclic compound: for example,

Formula 2.12′ has two copies of the recognition sequence (HX tandemly repeated and cyclized. A GLY is inserted to facilitate a turn.

Let

be an amino-acid analogue that forces a β turn; many of which are known in the art. Then compounds of formula 2.12 are likely to have the desired conformation and to show highly specific plasma kallikrein binding.

Related compounds encompassed in formula 2 include cyclic(PKANHQ

PKANHQ

; SEQ ID NO:50) and cyclic(HMKANHQ

HMKANHQ

; SEQ ID NO:51).

Furthermore, one might increase the specificity to 2.12 by replacing the P1 amino acid (K₄ and K₁₂) with a non-basic amino acid such as ALA, SER, or GLY.

Formula 2.13 embodies two copies of the NHQ subsequence, having the P1′ ALA replaced by PRO (to force the appropriate phi angle). Cyclic (ANHQ

ANHQ

; SEQ ID NO:53) is also a likely candidate for specific plasma kallikrein binding.

Also encompassed by formula-2 are compounds like that shown in FIG. 10 having the sequence cyclo(bis H-HIS-CYS-LYS-ALA-ASN-HIS-GLN*; SEQ ID NO:54) wherein GLN* is the modified moiety shown and the cycle is closed by two thioether linkages.

Pseudopeptides:

As used herein, a “pseudopeptide” is a linkage that connects two carbon atoms which correspond to the carbons of amino acids and which are called the “bridge-head atoms”. The pseudopeptide holds the bridge-head atoms at an appropriate separation, approximately 3.8 Å. The pseudopeptide is preferably planar, holding the bridge-head atoms in the same plane as most or all of the atoms of the pseudopeptide. Typically, a pseudopeptide has an amino group and a carboxylic acid group so that is corresponds roughly to a dipeptide that can be introduced into a peptide by standard Fmoc, tBoc, or other chemistry.

In BPTI, the carbonyl oxygen of K₁₅ projects toward the exterior while the amine nitrogen of A₁₆ points toward the interior of BPTI. Thus, psuedopeptides that preserve the carbonyl group are preferred over those that do not. Furthermore, pseudopeptides that favor the atomic arrangement found at residues 15 and 16 of Kunitz domains are particularly favored at residues 15-16 for compounds of the present invention. At other positions, pseudopeptides that favor the observed conformation are preferred.

FIGS. 1 and 2 show twelve examples of pseudopeptides; other pseudopeptides may be used. Of these, ψ1, ψ2, ψ3, ψ5, ψ6, ψ7, ψ8, ψ9, ψ11, and ψ12 maintain the same number of atoms between nominal C_(α)s. ψ4 and ψ10 add an extra atom in the linkage. ψ2, ψ4, ψ6, ψ7, ψ8, ψ9, and ψ10 maintain a carbonyl oxygen. ψ1, ψ3, ψ5, can carry electronegative groups in a place similar to that of the carbonyl oxygen if X₁ is F or —O-alkyl (especially —O—CH₃ or —O—CF₃). The pseudopeptide bond plays several roles. First, the pseudopeptide prevents hydrolysis of the bond. To do this, it is usually enough that the bond be stable in water and that at least one atom of the peptide be changed. It may be sufficient to alkylate the peptide amide. Peptides having PRO at P1′ are often highly resistant to cleavage by serine proteases. A second role of the pseudopeptide if to favor the desired conformation of the residues joined by the pseudopeptide. Thirdly, the pseudopeptide provides groups having suitable charge; hydrogen-bonding potential, and polarizability. Even so, it must be remembered that only a true peptide will have the same geometry, charge distribution, and flexibility as a peptide. Changing one atom will alter some property. In most cases, the binding of the pseudopeptide derivative to the target protease will be less tight than is the binding of the Kunitz domain from which sequence information was taken. Nevertheless, it is possible that some pseudopeptide derivatives will bind better than true peptides. To minimize the loss of affinity, it is desirable:

-   -   1) that the pseudopeptide itself be at least roughly planar,     -   2) that the pseudopeptide keep the two joined a carbons in the         plane of the pseudopeptide, and     -   3) that the separation of the two joined a carbons be         approximately 3.8 Å.         ψ1, ψ6, ψ7, ψ8, and ψ11 are expected to keep the α carbons in         the plane of the pseudopeptide. In ψ8 carbons 1, 2, and 6 plus         the carbonyl O define the plane of the pseudopeptide. ψ8 and ψ9         are likely to be approximately consistent with the geometry         between residues 15 and 16 of a Kunitz domain. The cyclohexone         or cyclohexenone ring does not conflict with groups that are         included in the compounds of the present invention, but would         conflict with atoms of a Kunitz domain.

Kline et al. (KLIN91) have reported use of —CH₂—CO—NH— and —CH₂—NH— in hirulogs that bind plasma kallikrein. DiMaio et al. (DIMA91) have reported using —CO—CH₂— as a pseudopeptide bond in hirulogs that bind plasma kallikrein. Angliker et al. (ANGL87) report synthesis of lysylfluoromethanes and that Ala-Phe-Lys-CH₂F is an active-centre-directed inhibitor of plasma kallikrein and trypsin.

3) Peptides Having the “Scissile Bond” Replaced by a Pseudopeptide:

A third class of likely plasma kallikrein inhibitors are those in which some or all of the peptide bonds are replaced by non-peptide bonds. Groups that replace peptide bonds in compounds derived from peptides are usually referred to as pseudopeptides and designated with the symbol ψ. The most important peptide bond to replace is the one between the P1 and P1′ residues, the so called “scissile bond”. Thus, compounds of the formula 3 or 3a are likely to be specific plasma kallikrein inhibitors.

X₁—X₂—X₃—X₄═X₅—X₆—X₇—X₈—X₉  Formula 3

X₁—X₂—X₃—X₄═X₅—X₆═X₇—X₈—X₉  Formula 3a

wherein:

-   -   the first residue may be 1, 2, 3, or 4, and the length of the         compound is at least 5 residues and not more than 9; the —X₄═X₅—         and —X₆═X₇— moieties being counted as two residues,     -   X₁ corresponds to the P4 residue the inhibitor and may be picked         from the set comprising {any d or l amino acid (having free or         blocked amino group) or an amino group (possibly blocked with         one of the groups acetyl, formyl, methyl, ethyl, propyl,         isopropyl, n-butyl, secondary butyl, tertiary butyl, benzyl, or         similar group)}; preferred choices are hydrogen, acetyl,         glycine, and formyl,     -   X₂ corresponds to the P3 residue and is most preferably l-HIS;         alternatives include (without limitation)         L-C^(δ)methylhistidine, L-C^(ε)methylhistidine,         L-p-aminophenylalanine, L-m-(N,N-dimethylamino)phenylalanine,         canavanine (Merck Index 1745), and N-methylasparagine; all the         alternatives have one or more of the properties: amphoteric,         aromatic, hydrophobic, and cyclic, as does HIS,     -   X₃ corresponds to the P2 residue and may be any 1 amino acid,         preferably uncharged and hydrophobic; if X₃ is cysteine, the         sulphur is blocked by one of a) a second cysteine residue, b) a         thiol reagent, c) an alkyl group, if X₃ is not cysteine, then         PRO is a preferred choice because the φ of CYS₁₄ is in the range         accessible to PRO and the side group of PRO is not dissimilar to         the disulfide group, other preferred alternatives at X₃ include         l-MET, l-GLN, l-pipecolic acid (Merck Index 7425),         l-2-azitidinecarboxylic acid (Merck Index 923), l-LEI, l-ILE,         l-VAL, cycloleucine (Merck Index 2740), l-α-aminobutylric acid,         1-aminocyclopropane-1-carboxylic acid, and l-methoxyalanine,     -   X₄ corresponds to the P1 residue and is most preferably l-LYS,         l-ARG, l-ornithine, or l-guanidolysine (i.e.         NH₂—CH(COOH)—(CH₂)₄—NH—C—(NH₂)₂+); l-ALA, l-SER, and GLY are         preferred alternatives,     -   = represents a suitable pseudopeptide that joins the side groups         of X₄ and X₃ and allows the side groups to be in a relative         orientation similar to that found for residues 15 and 16 of         Kunitz domains; φ₄ should be approximately −111°, ψ₄ should be         approximately 36°, φ₅ should be approximately −80°, ψ₅ should be         approximately 164°,     -   X₅ corresponds to the P1′ residue and is most preferably ALA if         X₄ is present; l-PRO, GLY, and l-SER are preferred alternatives;         X₅ may be any amino acid if X₁-X₄ are absent,     -   X₆ corresponds to the P2′ residue and is most preferably l-ASN,         l-SER, l-GLN; other amino acids having small, neutral,         hydrophilic groups, such as (but without limitation) O-methyl         serine, α-amidoglycine, α-aminobutyric acid, β-fluoroalanine,         N-methylasparagine, N,N-dimethylasparagine, and         α-amino-γ-hydroxybutyric acid (homoserine), are preferred         alternatives,     -   = (if present) is a suitable pseudopeptide that allows the side         groups of X₆ and X₇ to be in a suitable conformation, φ₆ should         be approximately −113°, ψ₆ should be approximately 85°, φ₇         should be approximately −110°, ψ₇ should be approximately 123°,     -   X₇ corresponds to the P3′ residue and is most preferably HIS;         preferred alternatives include, for example and without         limitation, L-C^(δ)methylhistidine, L-C^(ε)methylhistidine,         L-p-aminophenylalanine, L-m-(N,N-dimethylamino)phenylalanine,         canavanine (Merck Index 1745), and N-methylasparagine; all the         alternatives have one or more of the properties: amphoteric,         aromatic, hydrophobic, and cyclic, as does HIS,     -   X₈ corresponds to the P4′ residue and most preferably is GLN;         other neutral residues including, for example and without         limitation, ASN, α-amino-δ-amidoadipic acid, HIS, and         α-amino-ε-amidopimelic acid. The preferred alternative all have         minimal size and no charged groups, and     -   X₉ corresponds to the p5′ residue and may be any l- or d-amino         acid, preferably l-ARG, l-LEU, or l-ALA (which occur frequently         at this position of Kunitz Domains), or GLU, ASP, or other amino         acids having acidic side groups (which might interact with         plasma kallikrein in place of GLU₃₂ or GLU₃₁), or homoserine or         other amino acid having a hydroxyl, or X₉ may be a free or         blocked carboxyl group of X₈ or X₉ may be a free or blocked         amide group of X₈, if X₅ is the first amino acid, then X₉ is         present.

The compound VI shown in FIG. 5 can be incorporated in Fmoc synthesis of peptides to incorporate —X₄=GLY₅- of formulae 3.1 or 3.2. Other residue types can be introduced at residue 5. Compound VI leads to incorporation of ornithine=ALA which can be converted to ARG=ALA with N,N′-di-Cbz-S-methylisothiourea (TIAN92). If Cmpd I contained four methylene groups (instead of three), the following synthesis would lead to X₄=LYS. Compounds of the form of formula 3 in which X₄ is ornithine or guanidolysine are likely to be specific inhibitors of plasma kallikrein and should be tested. FIG. 5 shows intermediates involved in synthesis of VI. Compound. I is ornithine aldehyde with the α amino group blocked with Fmoc and the δ amino group blocked with allyloxycarbonyl. The aldehyde can be made by selective reduction of the N^(α)-Fmoc, N^(δ)-Aloc blocked l-ornithine acid (MARC85 p. 397), by reduction of the N^(α)-Fmoc, N^(δ)-Aloc blocked l-ornithine acid chloride (MARC85 p. 396), reduction of the N^(α)-Fmoc, N^(δ)-Aloc blocked l-ornithine amide (MARC85 p. 398), or by oxidation of the primary alcohol obtained by reduction of the N^(α)-Fmoc, N^(δ)-Aloc blocked l-ornithine acid with LiAlH₄ (MARC85, p. 1099). Oxidation of the alcohol is carried out with N-bromosuccinamide (MARC85, p. 1057).

Cmpd II is converted to a Grignard reagent and reacted with I; the product is III. The free hydrozyl of III is blocked with THP (CARE90, p. 678) and the MEM group is removed to give Cmpd IV. Cmpd IV is oxidized to the carboxylic acid, cmpd V. Cmpd V is then dehydrated to give VI. The synthesis of does not guarantee a trans double bond. The synthesis of VI given does not lead to a stereospecific product. There are chyral centers at carbons 2 and 6. Cmpd VI could, in any event, be purified by chromatography over an optically active substrate.

Other peptide bonds may be replaced with pseudopeptide bonds.

An option in cmpds of formula 3 is to link the side group of X₃ to the pseudopeptide so as to lock part of the main chain into the correct comformation for binding.

4) Cyclic Peptides Having a Pseudopeptide at the “Scissile Bond”

A fourth class of likely plasma kallikrein inhibitors are those in which some or all of the peptide bonds are replaced by non-peptide bonds and the compound is cyclized. The first peptide bond to replace is the one between the P1 and P1′ residues. Thus, compounds of formula 4 or 4a are likely to be specific inhibitors of plasma kallikrein.

wherein:

-   -   the first residue may be 1, 2, 3, or 4, and the length of the         compound is at least 5 residues and not more than 9; the —X₄═X₅—         and —X₆═X₂— moieties being counted as two residues,     -   X₁ corresponds to the P4 residue the inhibitor and may be picked         from the set comprising {any d or l amino acid (having free or         blocked amino group) or an amino group (possibly blocked with         one of the groups acetyl, formyl, methyl, ethyl, propyl,         isopropyl, n-butyl, secondary butyl, tertiary butyl, benzyl, or         similar group)}; preferred choices are hydrogen, acetyl,         glycine, and formyl,     -   X₂ corresponds to the P3 residue and is most preferably l-HIS;         alternatives include (without limitation)         L-C^(δ)methylhistidine, L-C^(ε)methylhistidine,         L-p-aminophenylalanine, L-m-(N,N-dimethylamino)phenylalanine,         canavanine (Merck Index 1745), and N-methylasparagine; all the         alternatives have one or more of the properties: amphoteric,         aromatic, hydrophobic, and cyclic, as does HIS,     -   X₃ corresponds to the P2 residue and may be any l amino acid,         preferably uncharged and hydrophobic; if X₃ is cysteine, the         sulphur is blocked by one of a) a second cysteine residue, b) a         thiol reagent, c) an alkyl group, if X₃ is not cysteine, then         PRO is a preferred choice because the φ of CYS₁₄ is in the range         accessible to PRO and the side group of PRO is not dissimilar to         the disulfide group, other preferred alternatives at X₃ include         l-MET, l-GLN, l-pipecolic acid (Merck Index 7425),         l-2-azitidinecarboxylic acid (Merck Index 923), l-LEU, l-VAL,         cycloleucine (Merck Index 2740), l-α-aminobutylric acid,         l-aminocyclopropane-l-carboxylic acid, and l-methoxyalanine,     -   X₄ corresponds to the P1 residue and is most preferably 1-LYS,         I-ARG, 1-ornithine, or l-guanidolysine (i.e.         NH₂—CH(COOH)—(CH₂)₄—NH—C—(NH₂)₂+); l-ALA, l-SER, and GLY are         preferred alternatives,     -   = represents a suitable pseudopeptide that joins the side groups         of X₄ and X₅ and allows the side groups to be in a relative         orientation similar to that found for residues 15 and 16 of         Kunitz domains; φ₄ should be approximately −111°, ψ₄ should be         approximately 36°, φ₅ should be approximately −80°, ψ₅ should be         approximately 164°,     -   X₅ corresponds to the P1′ residue and is most preferably ALA if         X₄ is present; l-PRO, GLY, and l-SER are preferred alternatives;         X₅ may be any amino acid if X₁-X₄ are absent,     -   X₆ corresponds to the P2′ residue and is most preferably l-ASN,         l-SER, l-GLN; other amino acids having small, neutral,         hydrophilic groups, such as (but without limitation) O-methyl         serine, α-amidoglycine, α-aminobutyric acid, β-fluoroalanine,         N-methylasparagine, N,N-dimethylasparagine, and         α-amino-γ-hydroxybutyric acid (homoserine), are preferred         alternatives,     -   = (if present) is a suitable pseudopeptide that allows the side         groups of X₆ and X₇ to be in a suitable conformation, 4)₆ should         be approximately −113°, ψ₆ should be approximately 85°, φ₇         should be approximately −110°, ψ₇ should be approximately 123°,     -   X⁷ corresponds to the P3′ residue and is most preferably HIS;         preferred alternatives include, for example and without         limitation, L-C^(δ)methylhistidine, L-C^(ε)methylhistidine,         L-p-aminophenylalanine; L-m-(N,N-dimethylamino)phenylalanine,         canavanine (Merck Index 1745), and N-methylasparagine; all the         alternatives have one or more of the properties: amphoteric,         aromatic, hydrophobic, and cyclic, ItS does HIS,     -   X₈ corresponds to the P4′ residue and most preferably is GLN;         other neutral residues including, for example and without         limitation, ASN, α-amino-δ-amidoadipic acid, HIS, and         α-amino-ε-amidopimelic acid. The preferred alternative all have         minimal size and no charged groups, and     -   X₉ corresponds to the p5′ residue and may be any l- or d-amino         acid, preferably l-ARG, l-LEU, or l-ALA (which occur frequently         at this position of Kunitz Domains), or GLU, ASP, or other amino         acids having acidic side groups (which might interact with         plasma kallikrein in place of GLU₃₂ or GLU₃₁), or homoserine or         other amino acid having a hydroxyl, or X₉ may be a free or         blocked carboxyl group of X₈ or X₉ may be a free or blocked         amide group of X₈; if X₅ is the first amino add, then X₉ is         present,     -   Linker may be a chain of carbon, nitrogen, oxygen, sulphur,         phosphorus, or other multivalent atoms. In BPTI (Brookhaven         Protein Data Bank entry 1TPA), N₁₃ is separated from C₁₉ by 14.6         Å. In aliphatic groups, carbon atoms are separated by about 1.54         Å and have bond angles of 109°; thus, an extended chain covers         about 1.25 Å per CH₂ group. Accordingly, a chain of about 12 or         more methylene groups would, span the gap and allow the         partially peptidyl chain to take up its preferred conformation.         Linkers that contain hydrophilic groups, such as —OH, —NH₂,         —COON, —O—CH₃, may improve solubility. Linkers that contain         aromatic groups (for example paraphenyl or 2,6 naphthylene) are         allowed. An alternative is a peptidyl linker. Peptidyl linkers         that are highly resistant to proteolysis are preferred. The gap         of 14.5 Å could be bridged by five or six residues. Thus,         sequences such as GPTVG, GPTITG, GPETD, GPTGE, GTVTGG, DGPTTS or         GPDFGS (SEQ ID NOs:55-61, respectively) would be appropriate.         PRO is preferred because it is resistant to proteolysis. THR,         VAL, and ILE are preferred because they favor extended         structure. Charged amino acids (ASP, GLU, LYS, and ARG) are         preferred because they improve solubility. GLY, SER, PRO, ASP,         and ASN are preferred at the ends because they facilitate the         needed turns. For plasma kallikrein binding, acidic groups near         the start of the linker are preferred.

FIG. 9 shows compounds 4.1 and 4.2 according to formula 4. Compound 4.1 has a linker consisting of —(CH₂)₁₂—. Although the linker is purely hydrophobic, compound 4.1 contains residues X₄ (LYS or ARG), ARG₆, and X₈ (ARG or LYS) which are all positively charged. Furthermore, the nitrogen of PRO₂ is not an amide nitrogen, but a secondary or tertiary amine which would probably be protonated in aqueous solution. Compound 4.2 differs from compound 4.1 in that two hydroxyl groups have been incorporated into the linker to improve solubility.

An option in cmpds of formula 4 is to link the side group of X₃ to the pseudopeptide so as to lock part of the main chain into the correct comformation for binding.

5) Compounds Having at Least Three Side Groups on Non-Peptide Framework:

A fifth class of inhibitors contains the side groups corresponding to those (using Kunitz domain numbering) of X₁₅ (ARG or LYS), HIS₁₈, ASN₁₇, GLN₁₉, GLU₃₂, GLU₃₁, HIS₁₃, and X₃₄ (X=SER or THR) supported by a non-peptide framework that hold the a carbon at the correct position and causes the α-β bond to be directed in the correct direction. In addition, GLY₁₂ is included, as desired. Furthermore, electronegative atoms which are hydrogen-bond acceptors are positioned where some or all of the carbonyl oxygens are found in BPTI. In addition, hydrogen-bond donors are positioned where some or all of the amido nitrogen are found in BPTI. A minimum number of peptide bonds are included.

In a preferred embodiment, organic compounds (known to be synthesizable) are considered as possible frameworks. Compounds that are fairly rigid are preferred. Compounds not known to give rise to toxic break-down products are preferred. Compounds that are reasonably soluble are preferred, but we are attaching three basic side groups, so this preference is not strong.

The four side groups thought to comprise the pharmacophore are used to judge the suitability of each framework. For plasma kallikrein, the side groups X₁₅ (ARG, LYS, or other basic amino acid), HIS₁₈, ASN₁₇, GLN₁₉, GLU₃₂, GLU₃₁, HIS₁₃, and X₃₄ (X=SER or THR) in the above formulae are taken as most important. The relative positions of these groups could be determined by X-ray diffraction or, NMR. A model based on BPTI may also be used. Table 40 shows the coordinates of BPTI.

Wilson et al. (WIL93) describe an algorithm for designing an organic moiety to substitute or a large segment of a protein and to hold crucial residues in the appropriate conformation for binding. Compounds of the present invention can be designed using the same mathematical algorithm. Where Wilson et al. identify bonds of the peptide backbone and seeks organic frameworks to hold remaining parts of the parental protein in place, we identify several bonds leading from the backbone to the side groups and replace the backbone with an organic or organometalic framework that holds only side groups or parts of side groups in place.

Mode of Production

The proteins of the present invention may be produced by any conventional technique, including

-   -   (a) nonbiological synthesis by sequential coupling of component         amino acids,     -   (b) production by recombinant DNA techniques in a suitable host         cell, and     -   (c) removal of undesired sequences from LACI and coupling of         synthetic replacement sequences

The proteins disclosed herein are preferably produced, recombinantly, in a suitable host, such as bacteria from the genera Bacillus, Escherichia, Salmonella, Erwinia, and yeasts from the genera Hansenula, Kluyveromyces, Pichia, Rhinosporidium, Saccharomyces, and Schizosaccharomyces, or cultured mammalian cells such as COS-1. The more preferred hosts are microorganisms of the species Pichia pastoris, Bacillus subtilis, Bacillus brevis, Saccharomyces cerevisiae, Escherichia coli and Yarrowia lipolytica. Any promoter, regulatable or constitutive, which is functional in the host may be used to control gene expression.

Preferably the proteins are secreted. Most preferably, the proteins are obtained from conditioned medium. It is not required that the proteins described herein be secreted. Secretion is the preferred route because proteins are more likely to fold correctly, can be produced in conditioned medium with few contaminants, and are less likely to be toxic to host cells.

Unless there is a specific reason to include glycogroups, we prefer proteins designed to lack N-linked glycosylation sites so that they can be expressed in a wide variety of organisms including: 1) E. coli, 2) B. subtilis, 3) P. pastoris, 4) S. cerevisiae, and 5) mammalian cells.

Many cells used for engineered secretion of fusion proteins are less than optimal because they produce proteases that degrade the fusion protein. Several means exist for reducing this problem. There are strains of cells that are deficient in one or another of the offending proteases; Baneyx and Georgiou (BANE90) report that E. coli OmpT (an outer surface protease) degrades fusion proteins secreted from E. coli. They stated that an OmpT− strain is useful for production of fusion proteins and that degP− and ompT− mutations are additive. Baneyx and Georgiou (BANE91) report a third genetic locus (ptr) where mutation can improve the yield of engineered fusions.

Van Dijl et al. (1992) report cloning, expression, and function of B. subtilis signal peptidase (SPase) in E. coli. They found that overexpression of the spase gene lead to increased expression of a heterologous fusion protein. Use of strains having augmented secretion capabilities is preferred.

Anba et al. (1988) found that addition of PMSF to the culture medium greatly improved the yield of a fusion of phosphate binding protein (PhoS) to human growth hormone releasing factor (mhGRF).

Other factors that may affect production of these and other proteins disclosed herein include: 1) codon usage (it is preferred to optimize the codon usage for the host to be used), signal sequence, 3) amino-acid sequence at intended processing sites, presence and localization of processing enzymes, deletion, mutation, or inhibition of various enzymes that might alter or degrade the engineered product and mutations that make the host more permissive in secretion (permissive secretion hosts are preferred).

Standard reference works setting forth the general principles of recombinant DNA technology include Watson, J. D. et al. Molecular Biology of the Gene, Volumes I and II, The Benjamin/Cummings Publishing Company, Inc., publisher, Menlo Park, Calif. (1987); Darnell, J. E. et al., Molecular Cell Biology, Scientific American Books, Inc., publisher, New York; N.Y. (1986); Lewin, B. M., Genes II, John Wiley & Sons, publishers, New York, N.Y. (1985); Old, R. W., et al. Principles of Gene Manipulation: An Introduction to Genetic Engineering, 2d edition, University of California Press, publisher, Berkeley, Calif. (1981); Sambrook, J. et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y. (1989); and Ausubel et al Current Protocols in Molecular Biology, Wiley Interscience, N.Y., (1987, 1992). These references are herein entirely incorporated by reference.

Preparation of Peptides

Chemical polypeptide synthesis is a rapidly evolving area in the art, and methods of solid phase polypeptide synthesis are well-described in the following references, hereby entirely incorporated by reference: (Merrifield, B., J. Amer. Chem. Soc. 85:2149-2154 (1963); Merrifield, B., Science 232:341-347 (1986); Wade, J. D. et al., Biopolymers 25:S21-S37 (1986); Fields, G. B., Int. J. Polypeptide Prot. Res. 35:161 (1990); MilliGen Report Nos. 2 and 2a, Millipore Corporation, Bedford, Mass., 1987) Ausubel et al, supra, and Sambrook et al, supra.

In general, as is known in the art, such methods involve blocking or protecting reactive functional groups, such as free amino, carboxyl and thio groups. After polypeptide bond formation, the protective groups are removed (or de-protected). Thus, the addition of each amino acid residue requires several reaction steps for protecting and deprotecting. Current methods utilize solid phase synthesis, wherein the C-terminal amino acid is covalently linked to an insoluble resin particle large enough to be separated from the fluid phase by filtration. Thus, reactants are removed by washing the resin particles with appropriate solvents using an automated programmed machine. The completed polypeptide chain is cleaved from the resin by a reaction which does not affect polypeptide bonds.

In the more classical method, known as the “tBoc method,” the amino group of the amino acid being added to the resin-bound C-terminal amino acid is blocked with tert-butyloxycarbonyl chloride (tBoc). This protected amino acid is reacted with the bound amino acid in the presence of the condensing agent dicyclohexylcarbodiimide, allowing its carboxyl group to form a polypeptide bond the free amino group of the bound amino acid. The amino-blocking group is then removed by acidification with trifluoroacetic acid (TFA); it subsequently decomposes into gaseous carbon dioxide and isobutylene. These steps are repeated cyclically for each additional amino acid residue. A more vigorous treatment with hydrogen fluoride (HF) or trifluoromethanesulfonyl derivatives is common at the end of the synthesis to cleave the benzyl-derived side chain protecting groups and the polypeptide-resin bond.

More recently, the preferred “Fmoc” technique has been introduced as an alternative synthetic approach, offering milder reaction conditions, simpler activation procedures and compatibility with continuous flow techniques. This method was used, e.g., to prepare the peptide sequences disclosed in the present application. Here, the α-amino group is protected by the base labile 9-fluorenylmethoxycarbonyl (Fmoc) group. The benzyl side chain protecting groups are replaced by the more acid labile t-butyl derivatives. Repetitive acid treatments are replaced by deprotection with mild base solutions, e.g., 20% piperidine in dimethylformamide (DMF), and the final HF cleavage treatment is eliminated. A TFA solution is used instead to cleave side chain protecting groups and the polypeptide resin linkage simultaneously.

At least three different polypeptide-resin linkage agents can be used: substituted benzyl alcohol derivatives that can be cleaved with 95% TFA to produce a polypeptide acid, methanolic ammonia to produce a polypeptide amide, or 1% TFA to produce a protected polypeptide which can then be used in fragment condensation procedures, as described by Atherton, E. et al., J. Chem. Soc. Perkin Trans. 1:538-546 (1981) and Sheppard, R. C. et al., Int. J. Polypeptide Prot. Res. 20:451-454 (1982). Furthermore, highly reactive Fmoc amino acids are available as pentafluorophenyl esters or dihydro-oxobenzotriazine esters derivatives, saving the step of activation used in the tBoc method.

Chemical Modification of Amino Acids

Covalent modifications of amino acids contained in proteins of interest are included within the scope of the present invention. Such modifications may be introduced into an epitopic peptide and/or alloantigenic peptide by reacting targeted amino acid residues of the polypeptide with an organic derivatizing agent that is capable of reacting with selected side chains or terminal residues. The following examples of chemical derivatives are provided by way of illustration and not by way of limitation.

Aromatic amino acids may be replaced with D- or L-naphylalanine, D- or L-Phenylglycine, D- or L-2-thieneylalanine, D- or L-1-, 2-, 3- or 4-pyreneylalanine, D- or L-3-thieneylalanine, D- or L-(2-pyridinyl)-alanine, D- or L-(3-pyridinyl)-alanine, D- or L-(2-pyrazinyl)-alanine, D- or L-(4-isopropyl)-phenylglycine, D-(trifluoromethyl)-phenylglycine, D-(trifluoromethyl)-phenylalanine, D-p-fluorophenylalanine, D- or L-p-biphenylphenylalanine, D- or L-p-methoxybiphenylphenylalanine, D- or L-2-indole-(alkyl)alanines, and D- or L-alkylainines where alkyl may be substituted or unsubstituted methyl, ethyl, propyl, hexyl, butyl, pentyl, iso-propyl, iso-butyl, sec-isotyl, iso-pentyl, non-acidic amino acids, of C1-C20.

Acidic amino acids can be substituted with non-carboxylate amino acids while maintaining a negative charge, and derivatives or analogs thereof, such as the non-limiting examples of (phosphono)-alanine, glycine, leucine, isoleucine, threonine, or serine; or sulfated (e.g., —SO₃H) threonine, serine, tyrosine.

Other substitutions may include unnatural hyroxylated amino acids may made by combining “alkyl” (as defined and exemplified herein) with any natural amino acid. Basic amino acids may be substituted with alkyl groups at any position of the naturally occurring amino acids lysine, arginine, ornithine, citrulline, or (guanidino)-acetic acid, or other (guanidino)alkyl-acetic acids, where “alkyl” is define as above. Nitrile derivatives (e.g., containing the CN-moiety in place of COOH) may also be substituted for asparagine or glutamine, and methionine sulfoxide may be substituted for methionine. Methods of preparation of such peptide derivatives are well known to one skilled in the art.

In addition, any amide linkage in any of the proteins can be replaced by a ketomethylene moiety, e.g. (—C(═O)—CH₂—) for (—(C═O)—NH—). Such derivatives are expected to have the property of increased stability to degradation by enzymes, and therefore possess advantages for the formulation of compounds which may have increased in vivo half lives, as administered by oral, intravenous, intramuscular, intraperitoneal, topical, rectal, intraocular, or other routes.

In addition, any amino acid representing a component of the said proteins can be replaced by the same amino acid but of the opposite chirality. Thus, any amino acid naturally occurring in the L-configuration (which may also be referred to as the R or S configuration, depending upon the structure of the chemical entity) may be replaced with an amino acid of the same chemical structural type, but of the opposite chirality, generally referred to as the D-amino acid but which can additionally be referred to as the R- or the S-, depending upon its composition and chemical configuration. Such derivatives have the property of greatly increased stability to degradation by enzymes, and therefore are advantageous in the formulation of compounds which may have longer in vivo half lives, when administered by oral, intravenous, intramuscular, intraperitoneal, topical, rectal, intraocular, or other routes.

Additional amino acid modifications of amino acids of proteins of the present invention may include the following: Cysteinyl residues may be reacted with alpha-haloacetates (and corresponding amines), such as 2-chloroacetic acid or chloroacetamide, to give carboxymethyl or carboxyamidomethyl derivatives. Cysteinyl residues may also be derivatized by reaction with compounds such as bromotrifluoroacetone, alpha-bromo-beta-(5-imidozoyl)propionic acid, chloroacetyl phosphate, N-alkylmaleimides, 3-nitro-2-pyridyl disulfide, methyl 2-pyridyl disulfide, p-chloromercuribenzoate, 2-chloromercuri-4-nitrophenol, or chloro-7-nitrobenzo-2-oxa-1,3-diazole.

Histidyl residues may be derivatized by reaction with compounds such as diethylprocarbonate e.g., at pH 5.5-7.0 because this agent is relatively specific for the histidyl side chain, and para-bromophenacyl bromide may also be used; e.g., where the reaction is preferably performed in 0.1 M sodium cacodylate at pH 6.0.

Lysinyl and amino terminal residues may be reacted with compounds such as succinic or other carboxylic acid anhydrides. Derivatization with these agents is expected to have the effect of reversing the charge of the lysinyl residues. Other suitable reagents for derivatizing alpha-amino-containing residues include compounds such as imidoesters/e.g., as methyl picolinimidate; pyridoxal phosphate; pyridoxal; chloroborohydride; trinitrobenzenesulfonic acid; O-methylisourea; 2,4 pentanedione; and transaminase-catalyzed reaction with glyoxylate.

Arginyl residues may be modified by reaction with one or several conventional reagents, among them phenylglyoxal, 2,3-butanedione, 1,2-cyclohexanedione, and ninhydrin according to known method steps. Derivatization of arginine residues requires that the reaction be performed in alkaline conditions because of the high pKa of the guanidine functional group. Furthermore, these reagents may react with the groups of lysine as well as the arginine epsilon-amino group.

The specific modification of tyrosyl residues per se is well-known, such as for introducing spectral labels into tyrosyl residues by reaction with aromatic diazonium compounds or tetranitromethane. N-acetylimidizol and tetranitromethane may be used to form O-acetyl tyrosyl species and 3-nitro derivatives, respectively.

Carboxyl side groups (aspartyl or glutamyl) may be selectively-modified by reaction with carbodiimides (R′—N—C—N—R′) such as 1-cyclohexyl-3-(2-morpholinyl-(4-ethyl) carbodiimide or 1-ethyl-3-(4-azonia-4,4-dimethylpentyl) carbodiimide. Furthermore, aspartyl and glutamyl residues may be converted to asparaginyl and glutaminyl residues by reaction with ammonium ions.

Glutaminyl and asparaginyl residues may be frequently deamidated to the corresponding glutamyl and aspartyl residues. Alternatively, these residues may be deamidated under mildly acidic conditions. Either form of these residues falls within the scope of the present invention.

Derivatization with bifunctional agents is useful for cross-linking the peptide to a water-insoluble support matrix or to other macromolecular carriers, according to known method steps. Commonly used cross-linking agents include, e.g., 1,1-bis(diazoacetyl)-2-phenylethane, glutaraldehyde, N-hydroxysuccinimide esters, for example, esters with 4-azidosalicylic acid, homobifunctional imidoesters, including disuccinimidyl esters such as 3,3′-dithiobis(succinimidylpropionate), and bifunctional maleimides such as bis-N-maleimido-1,8-octane. Derivatizing agents such as methyl-3-[(p-azidophenyl)dithio]propioimidate yield photoactivatable intermediates that are capable of forming crosslinks in the presence of light. Alternatively, reactive water-insoluble matrices such as cyanogen bromide-activated carbohydrates and the reactive substrates described in U.S. Pat. Nos. 3,969,287; 3,691,016; 4,195,128; 4,247,642; 4,229,537; and 4,330,440 (which are herein incorporated entirely by reference), may be employed for protein immobilization.

Other modifications of proteins of the present invention may include hydroxylation of proline and lysine, phosphorylation of hydroxyl groups of seryl or threonyl residues, methylation of the alpha-amino groups of lysine, arginine, and histidine side chains (T. E. Creighton, Proteins: Structure and Molecule Properties, W.H. Freeman & Co., San Francisco, pp. 79-86 (1983)), acetylation of the N-terminal amine, methylation of main chain amide residues (or substitution with N-methyl amino acids) and, in some instances, amidation of the C-terminal carboxyl groups, according to known method steps. Glycosylation is also possible.

Such derivatized moieties may improve the solubility, absorption, permeability across the blood brain barrier biological half life, and the like. Such moieties or modifications of proteins may alternatively eliminate or attenuate any possible undesirable side effect of the protein and the like. Moieties capable of mediating such effects are disclosed, for example, in Remington's Pharmaceutical Sciences, 16th ed., Mack Publishing Co., Easton, Pa. (1980).

Such chemical derivatives of proteins also may provide attachment to solid supports, including but not limited to, agarose, cellulose, hollow fibers, or other polymeric carbohydrates such as agarose, cellulose, such as for purification, generation of antibodies or cloning; or to provide altered physical properties, such as resistance to enzymatic degradation or increased antigenic properties, which is desired for therapeutic compositions comprising proteins of the present invention. Such peptide derivatives are well-known in the art, as well as method steps for making such derivatives using carbodiimides active esters of N-hydroxy succinimmide, or mixed anhydrides, as non-limiting examples.

Assays for Kallikrein Binding and Inhibition

The proteins may be assayed for kallikrein-binding activity by any conventional method. Scatchard (Ann NY Acad Sci (1949) 51:660-669) described a classical method of measuring and analyzing binding which has been applied to the binding of proteins. This method requires relatively pure protein and the ability to distinguish bound protein from unbound.

A second method appropriate for measuring the affinity of inhibitors for enzymes is to measure the ability of the inhibitor to slow the action of the enzyme. This method requires, depending on the speed at which the enzyme cleaves substrate and the availability of chromogenic or fluorogenic substrates, tens of micrograms to milligrams of relatively pure inhibitor.

A third method of determining the affinity of a protein for a second material is to have the protein displayed on a genetic package, such as M13, and measure the ability of the protein to adhere to the immobilized “second material”. This method is highly sensitive because the genetic packages can be amplified. We obtain at least semiquantitative values for the binding constants by use of a pH step gradient. Inhibitors of known affinity for the immobilized protease are used to establish standard profiles against which other phage-displayed inhibitors are judged.

Preferably, the proteins of the present invention have a binding activity against plasma kallikrein such that the complex has a dissociation constant of at most 200 pM, more preferably at most 50 pM. Preferably, their inhibitory activity is sufficiently high so that the Ki of binding with plasma kallikrein is less than 500 pM, more preferably less than 50 pM.

Pharmaceutical Methods and Preparations

The preferred animal subject of the present invention is a mammal. By the term “mammal” is meant an individual belonging to the class Mammalia. The invention is particularly useful in the treatment of human subjects, although it is intended for veterinary uses as well.

The term “protection”, as used herein, is intended to include “prevention,” “suppression” and “treatment.” “Prevention” involves administration of the protein prior to the induction of the disease. “Suppression” involves administration of the composition prior to the clinical appearance of the disease. “Treatment” involves administration of the protective composition after the appearance of the disease.

It will be understood that in human and veterinary medicine, it is not always possible to distinguish between “preventing” and “suppressing” since the ultimate inductive event or events may be unknown, latent, or the patient is not ascertained until well after the occurrence of the event or events. Therefore, it is common to use the term “prophylaxis” as distinct from “treatment” to encompass both “preventing” and “suppressing” as defined herein. The term “protection,” as used herein, is meant to include “prophylaxis.” It should also be understood that to be useful, the protection provided need not be absolute, provided that it is sufficient to carry clinical value. An agent which provides protection to a lesser degree than do competitive agents may still be of value if the other agents are ineffective for a particular individual, if it can be used in combination with other agents to enhance the level of protection, or if it is safer than competitive agents.

At least one of the proteins of the present invention may be administered, by any means that achieve their intended purpose, to protect a subject against a disease or other adverse condition. The form of administration may be systemic or topical. For example, administration of such a composition may be by various parenteral routes such as subcutaneous, intravenous, intradermal, intramuscular, intraperitoneal, intranasal, transdermal, or buccal routes. Alternatively, or concurrently, administration may be by the oral route. Parenteral administration can be by bolus injection or by gradual perfusion over time.

A typical regimen comprises administration of an effective amount of the protein, administered over a period ranging from a single dose, to dosing over a period of hours, days, weeks, months, or years.

It is understood that the suitable dosage of a protein of the present invention will be dependent upon the age, sex, health, and weight of the recipient, kind of concurrent treatment, if any, frequency of treatment, and the nature of the effect desired. However, the most preferred dosage can be tailored to the individual subject, as is understood and determinable by one of skill in the art, without undue experimentation. This will typically involve adjustment of a standard dose, e.g., reduction of the dose if the patient has a low body weight.

Prior to use in humans, a drug will first be evaluated for safety and efficacy in laboratory animals. In human clinical studies, one would begin with a dose expected to be safe in humans, based on the preclinical data for the drug in question, and on customary doses for analogous drugs (if any). If this dose is effective, the dosage may be decreased, to determine the minimum effective dose, if desired. If this dose is ineffective, it will be cautiously increased, with the patients monitored for signs of side effects. See, e.g., Berkow et al, eds., The Merck Manual, 15th edition, Merck and Co., Rahway, N.J., 1987; Goodman et al., eds., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th edition, Pergamon Press, Inc., Elmsford, N.Y., (1990); Avery's Drug Treatment: Principles and Practice of Clinical Pharmacology and Therapeutics, 3rd edition, ADIS Press, LTD., Williams and Wilkins, Baltimore, Md. (1987), Ebadi, Pharmacology, Little, Brown and Co., Boston, (1985), which references and references cited therein, are entirely incorporated herein by reference.

The total dose required for each treatment may be administered by multiple doses or in a single dose. The protein may be administered alone or in conjunction with other therapeutics directed to the disease or directed to other symptoms thereof.

The appropriate dosage form will depend on the disease, the protein, and the mode of administration; possibilities include tablets, capsules, lozenges, dental pastes, suppositories, inhalants, solutions, ointments and parenteral depots. See, e.g., Berker, supra, Goodman, supra, Avery, supra and Ebadi, supra, which are entirely incorporated herein by reference, including all references cited therein.

In addition to at least one protein as described herein, a pharmaceutical composition may contain suitable pharmaceutically acceptable carriers, such as excipients, carriers and/or auxiliaries which facilitate processing of the active compounds into preparations which can be used pharmaceutically. See, e.g., Berker, supra, Goodman, supra, Avery, supra and Ebadi, supra, which are entirely incorporated herein by reference, included all references cited therein.

In Vitro Diagnostic Methods and Reagents

The in vitro assays of the present invention may be applied to any suitable analyte-containing sample, and may be qualitative or quantitative in nature. In order to detect the presence, or measure the amount, of an analyte, the assay must provide for a signal producing system (SPS) in which there is a detectable difference in the signal produced, depending on whether the analyte is present or absent (or, in a quantitative assay, on the amount of the analyte). The detectable signal may be one which is visually detectable, or one detectable only with instruments. Possible signals include production of colored or luminescent products, alteration of the characteristics (including amplitude or polarization) of absorption or emission of radiation by an assay component or product, and precipitation or agglutination of a component or product. The term “signal” is intended to include the discontinuance of an existing signal, or a change in the rate of change of an observable parameter, rather than a change in its absolute value. The signal may be monitored manually or automatically.

The component of the signal producing system which is most intimately associated with the diagnostic reagent is called the “label”. A label may be, e.g., a radioisotope, a fluorophore, an enzyme, a co-enzyme, an enzyme substrate, an electron-dense compound, an agglutinable particle.

The radioactive isotope can be detected by such means as the use of a gamma counter or a scintillation counter or by autoradiography. Isotopes which are particularly useful for the purpose of the present invention are ³H, ¹²⁵I, ¹³¹I, ³⁵S, ¹⁴C, and, preferably, ¹²⁵I.

It is also possible to label a compound with a fluorescent, compound. When the fluorescently labeled antibody is exposed to light of the proper wave length, its presence can then be detected due to fluorescence. Among the most, commonly used fluorescent labelling compounds are fluorescein isothiocyanate, rhodamine, phycoerythrin, phycocyanin, allophycocyanin, o-phthaldehyde and fluorescamine.

Alternatively, fluorescence-emitting metals such as ¹²⁵Eu, or others of the lanthanide series, may be attached to the binding protein using such metal chelating groups as diethylenetriaminepentaacetic acid (DTPA) of ethylenediamine-tetraacetic acid (EDTA).

The binding proteins also can be detectably labeled by coupling to a chemiluminescent compound. The presence of the chemiluminescently labeled antibody is then determined by detecting the presence of luminescence that arises during the course of a chemical reaction. Examples of particularly useful chemiluminescent labeling compounds are luminol, isolumino, theromatic acridinium ester, imidazole, acridinium salt and oxalate ester.

Likewise, bioluminescent compound may be used to label the binding protein. Bioluminescence is a type of chemiluminescence found in biological systems in which a catalytic protein increases the efficiency of the chemiluminescent reaction. The presence of a bioluminescent protein is determined by detecting the presence of luminescence. Important bioluminescent compounds for purposes of labeling are luciferin, luciferase and aequorin.

Enzyme labels, such as horseradish peroxidase and alkaline phosphatase, are preferred. When an enzyme label is used, the signal producing system must also include a substrate for the enzyme. If the enzymatic reaction product is not itself detectable, the SPS will include one or more additional reactants so that a detectable product appears.

Assays may be divided into two basic types, heterogeneous and homogeneous. In heterogeneous assays, the interaction between the affinity molecule and the analyte does not affect the label, hence, to determine the amount or presence of analyte, bound label must be separated from free label. In homogeneous assays, the interaction does affect the activity of the label, and therefore analyte levels can be deduced without the need for a separation step.

In general, a kallikrein-binding protein (KBP) may be used diagnostically in the same way that an antikallikrein antibody is used. Thus, depending on the assay format, it may be used to assay Kallikrein, or by competitive inhibition, other substances which bind Kallikrein. The sample will normally be a biological fluid, such as blood, urine, lymph, semen, milk, or cerebrospinal fluid, or a fraction or derivative thereof, or a biological tissue, in the form of, e.g., a tissue section or homogenate. However, the sample conceivably could be (or derived from) a food or beverage, a pharmaceutical or diagnostic composition, soil, or surface or ground water. If a biological fluid or tissue, it may be taken from a human or other mammal, vertebrate or animal, or from a plant. The preferred sample is blood, or a fraction or derivative thereof.

In one embodiment, the kallikrein-binding protein is insolubilized by coupling it to a macromolecular support, and kallikrein in the sample is allowed to compete with a known quantity of a labeled or specifically labelable kallikrein analogue. The “kallikrein analogue” is a molecule capable of competing with kallikrein for binding to the KBP, and the term is intended to include kallikrein itself. It may be labeled already, or it may be labeled subsequently by specifically binding the label to a moiety differentiating the kallikrein analogue from kallikrein. The solid and liquid phases are separated, and the labeled kallikrein analogue in one phase is quantified. The higher the level of kallikrein analogue in the solid phase, i.e., sticking to the KBP, the lower the level of kallikrein analyte in the sample.

In a “sandwich assay”, both an insolubilized kallikrein-binding protein, and a labeled kallikrein-binding protein are employed. The kallikrein analyte is captured by the insolubilized kallikrein-binding protein and is tagged by the labeled KBP, forming a tertiary complex. The reagents may be added to the sample in either order, or simultaneously. The kallikrein-binding proteins may be the same or different, and only one need be a KBP according to the present invention (the other may be, e.g., an antibody or a specific binding fragment thereof). The amount of labeled KBP in the tertiary complex is directly proportional to the amount of kallikrein analyte in the sample.

The two embodiments described above are both heterogeneous assays. However, homogeneous assays are conceivable. The key is that the label be affected by whether or not the complex is formed.

The kallikrein analyte may act as its own label if a kallikrein inhibitor is used as a diagnostic reagent.

A label may be conjugated, directly or indirectly (e.g., through a labeled anti-KBP antibody), covalently (e.g., with SPDP) or noncovalently, to the kallikrein-binding protein, to produce a diagnostic reagent. Similarly, the kallikrein binding protein may be conjugated to a solid-phase support to form a solid phase (“capture”) diagnostic reagent. Suitable supports include glass, polystyrene, polypropylene, polyethylene, dextran, nylon, amylases, natural and modified celluloses, polyacrylamides, agaroses, and magnetite. The nature of the carrier can be either soluble to some extent or insoluble for the purposes of the present invention. The support material may have virtually any possible structural configuration so long as the coupled molecule is capable of binding to its target. Thus the support configuration may be spherical, as in a bead, or cylindrical, as in the inside surface of a test tube, or the external surface of a rod. Alternatively, the surface may be flat such as a sheet, test strip, etc.

In Vivo Diagnostic Uses

Kunitz domains that bind very tightly to proteases that are causing pathology can be used for in vivo imaging. Diagnostic imaging of disease foci is considered one of the largest commercial opportunities for monoclonal antibodies. This opportunity has not, however, been achieved. Despite considerable effort and resources, to date only one monoclonal antibody-based imaging agent has received regulatory approval. The disappointing results obtained with monoclonal antibodies is due in large measure to:

-   -   i) Inadequate affinity and/or specificity;     -   ii) Poor penetration to target sites;     -   iii) Slow clearance from nontarget sites;     -   iv) Immunogenicity, most are mouse antibodies; and     -   v) High production cost and poor stability.         These limitations have led most in the diagnostic imaging field         to begin to develop peptide-based imaging agents. While         potentially solving the problems of poor penetration and slow         clearance, peptide-based imaging agents are unlikely to possess         adequate affinity, specificity and in vivo stability to be         useful in most applications.

Engineered proteins are uniquely suited to the requirements for an imaging agent. In particular the extraordinary affinity and specificity that is obtainable by engineering small, stable, human-origin protein domains having known in vivo clearance rates and mechanisms combine to provide earlier, more reliable results, less toxicity/side effects, lower production and storage cost, and greater convenience of label preparation. Indeed, it should be possible to achieve the goal of realtime imaging with engineered protein imaging agents. Thus, a Kallikrein-binding protein, e.g., KKII/3#6 (SEQ ID NO:7), may be used for localizing sites of excessive pKA activity.

Radio-labelled binding protein may be administered to the human or animal subject. Administration is typically by injection, e.g., intravenous or arterial or other means of administration in a quantity sufficient to permit subsequent dynamic and/or static imaging using suitable radio-detecting devices. The preferred dosage is the smallest amount capable of providing a diagnostically effective image, and may be determined by means conventional in the art, using known radio-imaging agents as a guide.

Typically, the imaging is carried out on the whole body of the subject, or on that portion of the body or organ relevant to the condition or disease under study. The radio-labelled binding protein has accumulated. The amount of radio-labelled binding protein accumulated at a given point in time in relevant target organs can then be quantified.

A particularly suitable radio-detecting device is a scintillation camera, such as a gamma camera. A scintillation camera is a stationary device that can be used to image distribution of radio-labelled binding protein. The detection device in the camera senses the radioactive decay, the distribution of which can be recorded. Data produced by the imaging system can be digitized. The digitized information can be analyzed over time discontinuously or continuously. The digitized data can be processed to produce images, called frames, of the pattern of uptake of the radio-labelled binding protein in the target organ at a discrete point in time. In most continuous (dynamic) studies, quantitative data is obtained by observing changes in distributions of radioactive decay in target organs over time. In other words, a time-activity analysis of the data will illustrate uptake through clearance of the radio-labelled binding protein by the target organs with time.

Various factors should be taken into consideration in selecting an appropriate radioisotope. The radioisotope must be selected with a view to obtaining good quality resolution upon imaging, should be safe for diagnostic use in humans and animals, and should preferably have a short physical half-life so as to decrease the amount of radiation received by the body. The radioisotope used should preferably be pharmacologically inert, and, in the quantities administered, should not have any substantial physiological effect.

The binding protein may be radio-labelled with different isotopes of iodine, for example ¹²³I, ¹²⁵I, or ¹³¹I (see for example, U.S. Pat. No. 4,609,725). The extent of radio-labeling must, however be monitored, since it will affect the calculations made based on the imaging results (i.e. a diiodinated binding protein will result in twice the radiation count of a similar monoiodinated binding protein over the same time frame).

In applications to human subjects, it may be desirable to use radioisotopes other than ¹²⁵I for labelling in order to decrease the total dosimetry exposure of the human body and to optimize the detectability of the labelled molecule (though this radioisotope can be used if circumstances require). Ready availability for clinical use is also a factor. Accordingly, for human applications, preferred radio-labels are for example, ^(99m)Tc, ⁶⁷Ga, ⁶⁸Ga, ⁹⁰Y, ¹¹¹In, ^(113m)In, ¹²³I, ¹⁸⁶Re, ¹⁸⁸Re or ²¹¹At.

The radio-labelled protein may be prepared by various methods. These include, radio-halogenation by the chloramine-T method or the lactoperoxidase method and subsequent purification by HPLC (high pressure liquid chromatography), for example as described by J. Gutkowska et al in “Endocrinology and Metabolism Clinics of America: (1987) 16 (1):183. Other known method of radio-labelling can be, used, such as IODOBEADS™.

There are a number of different methods of delivering the radio-labelled protein to the end-user. It may be administered by any means that enables the active agent to reach the agent's site of action in the body of a mammal. Because proteins are subject to bering digested when administered orally, parenteral administration, i.e., intravenous subcutaneous, intramuscular, would ordinarily be used to optimize absorption.

High-affinity, high-specificity inhibitors are also useful for in vitro diagnostics of excess human pKA activity.

Other Uses

The kallikrein-binding proteins of the present invention may also be used to purify kallikrein from a fluid, e.g., blood. For this purpose, the KBP is preferably immobilized on a solid-phase support. Such supports, include those already mentioned as useful in preparing solid phase diagnostic reagents.

Proteins, in general, can be used as molecular weight markers for reference in the separation or purification of proteins by electrophoresis or chromatography. In many instances, proteins may need to be denatured to serve as molecular weight markers. A second general utility for proteins is the use of hydrolyzed protein as a nutrient source. Hydrolyzed protein is commonly used as a growth media component for culturing microorganisms, as well as a food ingredient for human consumption. Enzymatic or acid hydrolysis is normally carried out either to completion, resulting in free amino acids, or partially, to generate both peptides and amino acids. However, unlike acid hydrolysis, enzymatic hydrolysis (proteolysis) does not remove non-amino acid functional groups that may be present. Proteins may also be used to increase the viscosity of a solution.

The proteins of the present invention may be used for any of the foregoing purposes, as well as for therapeutic and diagnostic purposes as discussed further earlier in this specification.

Example 1 Construction of LACI (K1) Library

A synthetic oligonucleotide duplex having NsiI- and MluI-compatible ends was cloned into a parental vector (LACI:III) previously cleaved with the above two enzymes. The resultant ligated material was transfected by electroporation into XLIMR (F−) Escherichia coli strain and plated on Amp plates to obtain phage-generating Ap^(R) colonies. The variegation scheme for Phase 1 focuses on the P1 region, and affected residues 13, 16, 17, 18 and 19. It allowed for 6.6×10⁵ different DNA sequences (3.1×10⁵ different protein sequences). The library obtained consisted of 1.4×10⁶ independent cfu's which is approximately a two fold representation of the whole library. The phage stock generated from this plating gave a total titer of 1.4×10¹³ pfu's in about 3.9 ml, with each independent clone being represented, on average, 1×10⁷ in total and 2.6×10⁶ times per ml of phage stock.

To allow for variegation of residues 31, 32, 34 and 39 (phase II), synthetic oligonucleotide duplexes with MluI- and BstEII-compatible ends were cloned into previously cleaved R_(f) DNA derived from one of the following

-   -   i) the parental construction,     -   ii) the phase I library, or     -   iii) display phage selected from the first phase binding to a         given target.         The variegation scheme for phase II allows for 4096 different         DNA sequences (1600 different protein sequences) due to         alterations at residues 31, 32, 34 and 39. The final phase II         variegation is dependent upon the level of variegation remaining         following the three rounds of binding and elution with a given         target in phase I.

The combined possible variegation for both phases equals 2.7×10⁸ different DNA sequences or 5.0×10⁷ different protein sequences. When previously selected display phage are used as the origin of R_(f) DNA for the phase II variegation, the final level of variegation is probably in the range of 10⁵ to 10⁶.

Example 2 Screening of LACI (K1) Library for Binding to Kallikrein

The overall scheme for selecting a LACI(K1) variant to bind to a given protease involves incubation of the phage-display library with the kallikrein-beads of interest in a buffered solution (PBS containing 1 mg/ml BSA) followed by washing away the unbound and poorly retained display-phage variant with PBS containing 0.1% Tween 20. Kallikrein beads were made by coupling human plasma Kallikrein (Calbiochem, San Diego, Calif., #420302) to agarose beads using Reactigel (6×) (Pierce, Rockford, Ill., #202606). The more strongly bound display-phage are eluted with a low pH elution buffer, typically citrate buffer (pH 2.0) containing 1 mg/ml BSA, which is immediately neutralized with Tris buffer to pH 7.5. This process constitutes a single round of selection.

The neutralized eluted display-phage can be either used:

-   -   i) to inoculate an F⁺ strain of E. coli to generate a new         display-phage stock, to be used for subsequent rounds of         selection (so-called conventional screening), or     -   ii) be used directly for another immediate round of selection         with the protease beads (so-called quick screening).         Typically, three rounds of either method, or a combination of         the two, are performed to give rise to the final selected         display-phage from which a representative number are sequenced         and analyzed for binding properties either as pools of         display-phage or as individual clones.

Two phases of selection were performed, each consisting of three rounds of binding and elution. Phase I selection used the phase I library (variegated residues 13, 16, 17, 18, and 19) which went through three rounds of binding and elution against a target protease giving rise to a subpopulation of clones. The R_(f)DNA derived from this selected subpopulation was used to generate the Phase II library (addition of variegated residues 31, 32, 34 and 39). The 1.8×10⁷ independent transformants were obtained for each of the phase II libraries. The phase II libraries underwent three further rounds of binding and elution with the same target protease giving rise to the final selectants.

Following two phases of selection against human plasma kallikrein-agarose beads a number (10) of the final selection display-phage were sequenced. Table 6 shows the amino acids found at the variegated positions of LACI-K1 in the selected phage. Table 18 shows the complete sequences of the displayed proteins.

Table 23 shows that KkII/3(D) is a highly specific inhibitor of human Kallikrein. Phage that display the LACI-K1 derivative KkII/3(D) bind to Kallikrein beads at least 50-times more than it binds to other protease targets.

Preliminary measurements indicate that KKII/3#6 (SEQ ID NO:7) is a potent inhibitor of pKA with K_(i) probably less than 500 μM.

All references, including those to U.S. and foreign patents or patent applications, and to nonpatent disclosures, are hereby incorporated by reference in their entirety.

TABLE 6 Amino acid sequences of LACI(K1) variants selected for binding to human plasma kallikrein. 13 16 17 18 19 31 32 34 39(a) KKII/ (SEQ ID NO: 2) H A S L P E E I E 3#1 KKII/ (SEQ ID NO: 3) P A N H L E E S G 3#2 KKII/ (SEQ ID NO: 4) H A N H Q E E T G 3#3 KKII/ (SEQ ID NO: 5) H A N H Q E Q T A 3#4 KKII/ (SEQ ID NO: 6) H A S L P E E I G 3#5 KKII/ (SEQ ID NO: 7) H A N H Q E E S G 3#6 KKII/ (SEQ ID NO: 8) H A N H Q E E S G 3#7 KKII/ (SEQ ID NO: 9) H A N H Q E E S G 3#8 KKII/ (SEQ ID NO: 10) H A N H Q E E S G 3#9 KKII/ (SEQ ID NO: 11) H G A H L E E I E 3#10 Con- H A N H Q E E S/T G sen- sus (a)Amino acid numbers of variegated residues. LACI (K1) (residues 50-107 of SEQ ID NO: 25) is 58 amino acids long with the P1 position being residue number 15 and fixed as lysine in this instance. Whole sequences given in Table 18

TABLE 7 Kallikrein-binding display-phage chosen for further analysis. 13 16 17 18 19 31 32 34 39 KKII/ (SEQ ID NO: 7) H A N H Q E E S G 3#6 KKII/ (SEQ ID NO: 6) H A S L P E E I G 3#5 KKI/ (SEQ ID NO: 13) P A I H L E E I E 3(b) KKI/ (SEQ ID NO: 12 R G A H L E E I E 3(a) LACI (residues 50-107 P A I M K E E I E* (K1) of SEQ ID NO: 25) BPTI (SEQ ID NO: 1) P A R I I Q T V R** (Note that clones a and b are from the first phase of screening and as such have a wild type sequence at residues 31 to 39. *Parental molecule. **Control (bovine pancreatic trypsin inhibitor.)

Whole sequences given in Table 18 and Table 17 (BPTI)

TABLE 8 Binding Data for Selected Kallikrein-binding Display-Phage. Fraction Relative Display-Phage (a) Bound (b) Binding (c) LACI (residues 50-107 4.2 × 10−6 1.0 of SEQ ID NO: 25) BPTI (SEQ ID NO: 1) 2.5 × 10−6 6.0 KKI/3(a) (SEQ ID NO: 12) 3.2 × 10−5 761 KKI/3(b) (SEQ ID NO: 13) 2.2 × 10−3 524 KKII/3#5 (SEQ ID NO: 6) 3.9 × 10−3 928 KKII/3#6 (SEQ ID NO: 7) 8.7 × 10−3 2071 (a) Clonal isolates of display-phage. LACI(K1) is the parental molecule, BPTI (bovine pancreatic trypsin inhibitor) is a control and KKII/3 (5 and 6) and KKI/3(a and b) were selected by binding to the target protease, kallikrein. (b) The number of pfu's eluted after a binding experiment as a fraction of the input number (10¹⁰ pfu's). (c) Fraction bound relative to the parental display-phage, LACI(K1).

TABLE 17 Amino-acid sequence of BPT1          1         2         3         4         5 1234567890123456789012345678901234567890123456789012345678 RPDFCLEPPYTGPCKARIIRYFYNAKAGLCQTFVYGGCRAKRNNFKSAEDCMRTCGGA (SEQ ID NO: 1)

TABLE 18 Sequence of LACI-K1 and derivatives that bind human plasma  kallikrein          1         2         3         4         5 1234567890123456789012345678901234567890123456789012345678 LACI-K1 mhsfcafkaddgpckaimkrfffniftrqceefiyggcegnqnrfesleeckkmctrd (residues 50-107 of SEQ ID NO: 25) KKII/3#1 mhsfcafkaddgHckASLPrfffniftrqcEEfIyggcEgnqnrfesleeckkmctrd (SEQ ID NO: 2) KKII/3#2 mhsfcafkaddgPckANHLrfffniftrqcEEfSyggcGgnqnrfesleeckkmctrd (SEQ ID NO: 3) KKII/3#3 mhsfcafkaddgHckANHQrfffniftrqcEEfTyggcGgnqnrfesleeckkmctrd (SEQ ID NO: 4) KKII/3#4 mhsfcafkaddgHckANHQrfffniftrqcEQfTyggcAgnqnrfesleeckkmctrd (SEQ ID NO: 5) KKII/3#5 mhsfcafkaddgHckASLPrfffniftrqcEEfIyggcGgnqnrfesleeckkmctrd (SEQ ID NO: 6) KKII/3#6 mhsfcafkaddgHckANHQrfffniftrqcEEfSyggcGgnqnrfesleeckkmctrd (SEQ ID NO: 7) KKII/3#7 mhsfcafkaddgHckANHQrfffniftrqcEEfSyggcGgnqnrfesleeckkmctrd (SEQ ID NO: 8) KKII/3#8 mhsfcafkaddgHckANHQrfffniftrqcEEfSyggcGgnqnrfesleeckkmctrd (SEQ ID NO: 9) KKII/3#9 mhsfcafkaddgHckANHQrfffniftrqcEEfSyggcGgnqnrfesleeckkmctrd (SEQ ID NO: 10) KKII/3#10 mhsfcafkaddgHckGAHLrfffniftrqcEEfIyggcEgnqnrfesleeckkmctrd (SEQ ID NO: 11) KKII/3 (a) mhsfcafkaddgRckGAHLrfffniftrqceefiyggcegnqnrfesleeckkmctrd (SEQ ID NO: 12) KKII/3 (b) mhsfcafkaddgPckAIHLrfffniftrqceefiyggcegnqnrfesleeckkmctrd (SEQ ID NO: 13) KKII/3 #C mhsfcafkaddgHckANHQrfffniftrqcEEfSyggcGgnqnrfesleeckkmctrd (SEQ ID NO: 14)

TABLE 21 Variegation of LACI-K1

The segment from NsiI to MluI gives 65,536 DNA sequences and 31,200 protein sequences. Second group of variegation gives 21,840 and 32,768 variants. This variegation can go in on a fragment having MluI and one of AgeI, BstBI, or XbaI ends. Because of the closeness between codon 42 and the 3′ restriction site, one will make a self-priming oligonucleotide, fill in, and cut with MluI and, for example, BstBI. Total variants are 2.726 × 10⁹ and 8.59 × 10⁹.

TABLE 23 Specificity Results Target Trypsin, Display Plasmin Thrombin Kallikrein Trypsin two washes LACI-K1¹ 1.0 1.0 1.0 1.0 1.0 KkII/3(D)² 3.4 1.5 196 2.0 1.4 BPTI::III³ (88)⁴    (1.1) (1.7) (0.3) (0.8) numbers refer to relative binding of phage display clo4nes compared to the parental phage display. The KkII/3(D)(Kallikrein) clone retains the parental molecule's affinity for trypsin. ¹Displayed on Ml3 III. ²Selected for plasma kallikrein binding. ³Control. ⁴BPTI relative to LACI.

TABLE 40 Coordinates of BPTI (1TPA) N ARG 1 11.797 100.411 6.463 CA ARG 1 12.697 101.495 6.888 C ARG 1 13.529 101.329 8.169 O ARG 1 14.755 101.605 8.115 CB ARG 1 12.037 102.886 6.801 CG ARG 1 13.107 103.969 6.578 CD ARG 1 12.560 105.405 6.648 NE ARG 1 13.682 106.329 6.443 CZ ARG 1 13.570 107.597 6.106 NH1 ARG 1 12.380 108.144 5.959 NH2 ARG 1 14.657 108.320 5.922 N PRO 2 12.931 101.060 9.332 CA PRO 2 13.662 101.101 10.617 C PRO 2 14.678 99.990 10.886 O PRO 2 14.239 98.887 11.277 CB PRO 2 12.604 100.958 11.726 CG PRO 2 11.250 100.694 11.051 CD PRO 2 11.489 100.823 9.539 N ASP 3 15.885 100.463 11.149 CA ASP 3 17.078 99.909 11.973 C ASP 3 17.125 98.489 12.483 O ASP 3 18.085 97.801 12.106 CB ASP 3 17.819 100.822 12.981 CG ASP 3 18.284 100.049 14.210 OD1 ASP 3 17.667 100.236 15.287 OD2 ASP 3 19.492 99.710 14.278 N PHE 4 16.069 97.949 13.050 CA PHE 4 15.939 96.466 13.148 C PHE 4 15.865 95.753 11.765 O PHE 4 16.126 94.534 11.580 CB PHE 4 14.817 96.062 14.145 CG PHE 4 13.386 96.292 13.636 CD1 PHE 4 12.801 95.382 12.783 CD2 PHE 4 12.735 97.447 13.940 CE1 PHE 4 11.539 95.602 12.260 CE2 PHE 4 11.482 97.684 13.408 CZ PHE 4 10.879 96.748 12.582 N CYS 5 15.456 96.498 10.755 CA CYS 5 15.358 95.949 9.416 C CYS 5 16.745 95.732 8.840 O CYS 5 16.856 95.011 7.838 CB CYS 5 14.653 96.970 8.534 SG CYS 5 12.907 97.271 8.905 N LEU 6 17.765 96.247 9.497 CA LEU 6 19.110 96.026 9.002 C LEU 6 19.777 94.885 9.731 O LEU 6 20.896 94.493 9.322 CB LEU 6 19.986 97.263 9.235 CG LEU 6 19.438 98.493 8.493 CD1 LEU 6 20.291 99.703 8.860 CD2 LEU 6 19.261 98.356 6.971 N GLU 7 19.122 94.342 10.725 CA GLU 7 19.755 93.241 11.464 C GLU 7 19.711 91.890 10.740 O GLU 7 18.873 91.648 9.852 CB GLU 7 19.232 93.163 12.914 CG GLU 7 19.336 94.483 13.695 CD GLU 7 18.778 94.225 15.092 OE1 GLU 7 18.815 93.054 15.548 OE2 GLU 7 17.924 95.019 15.561 N PRO 8 20.765 91.108 10.862 CA PRO 8 20.839 89.797 10.262 C PRO 8 19.790 88.842 10.860 O PRO 8 19.233 89.114 11.944 CB PRO 8 22.244 89.267 10.608 CG PRO 8 22.754 90.131 11.757 CD PRO 8 21.882 91.377 11.769 N PRO 9 19.319 87.911 10.080 CA PRO 9 18.232 87.056 10.487 C PRO 9 18.694 86.135 11.628 O PRO 9 19.855 85.673 11.592 CB PRO 9 17.905 86.208 9.266 CG PRO 9 19.171 86.263 8.426 CD PRO 9 19.774 87.618 8.743 N TYR 10 17.829 85.920 12.619 CA TYR 10 18.072 85.128 13.831 C TYR 10 17.277 83.837 13.923 O TYR 10 16.039 83.903 14.101 CB TYR 10 17.700 86.057 15.008 CG TYR 10 18.105 85.479 16.355 CD1 TYR 10 17.163 85.154 17.302 CD2 TYR 10 19.449 85.291 16.610 CE1 TYR 10 17.586 84.599 18.519 CE2 TYR 10 19.872 84.762 17.821 CZ TYR 10 18.945 84.405 18.771 OH TYR 10 19.413 83.745 19.968 N THR 11 17.930 82.728 13.743 CA THR 11 17.250 81.464 13.910 C THR 11 16.905 81.173 15.365 O THR 11 15.806 80.629 15.663 CB THR 11 18.157 80.342 13.426 OG1 THR 11 18.374 80.467 12.011 CG2 THR 11 17.587 78.955 13.770 N GLY 12 17.800 81.499 16.276 CA GLY 12 17.530 81.172 17.717 C GLY 12 17.795 79.707 18.130 O GLY 12 18.093 78.812 17.294 N PRO 13 17.594 79.422 19.438 CA PRO 13 18.020 78.175 20.067 C PRO 13 17.028 77.024 19.943 O PRO 13 17.521 75.872 19.887 CB PRO 13 18.118 78.476 21.544 CG PRO 13 17.139 79.617 21.758 CD PRO 13 17.023 80.360 20.414 N CYS 14 15.735 77.328 19.666 CA CYS 14 14.732 76.275 19.385 C CYS 14 14.880 75.629 18.020 O CYS 14 15.608 76.158 17.146 CB CYS 14 13.299 76.717 19.613 SG CYS 14 12.983 77.300 21.278 N LYS 15 14.500 74.402 17.967 CA LYS 15 14.776 73.485 16.889 C LYS 15 13.544 73.079 16.047 O LYS 15 13.540 71.988 15.436 CB LYS 15 15.423 72.254 17.559 CG LYS 15 16.816 72.596 18.149 CD LYS 15 17.559 71.326 18.616 CE LYS 15 18.900 71.636 19.321 NZ LYS 15 19.518 70.412 19.904 N ALA 16 12.618 73.966 15.829 CA ALA 16 11.683 73.785 14.691 C ALA 16 12.409 74.246 13.418 O ALA 16 13.458 74.945 13.471 CB ALA 16 10.368 74.627 14.903 N ARG 17 11.872 73.853 12.310 CA ARG 17 12.256 74.420 11.018 C ARG 17 11.079 75.215 10.439 O ARG 17 10.278 74.719 9.613 CB ARG 17 12.733 73.245 10.174 CG ARG 17 13.392 73.661 8.858 CD ARG 17 12.294 74.044 7.852 NE ARG 17 12.786 73.577 6.649 CZ ARG 17 12.596 72.435 6.095 NH1 ARG 17 11.637 71.610 6.379 NH2 ARG 17 13.299 72.211 5.023 N ILE 18 10.949 76.457 10.831 CA ILE 18 9.848 77.334 10.377 C ILE 18 10.312 78.435 9.443 O ILE 18 11.321 79.098 9.777 CB ILE 18 9.158 77.976 11.596 CG1 ILE 18 8.479 76.864 12.430 CG2 ILE 18 8.132 79.053 11.235 CD1 ILE 18 8.302 77.409 13.857 N ILE 19 9.724 78.469 8.238 CA ILE 19 10.176 79.438 7.218 C ILE 19 9.523 80.797 7.401 O ILE 19 8.274 80.911 7.406 CB ILE 19 10.074 78.910 5.754 CG1 ILE 19 10.860 77.594 5.658 CG2 ILE 19 10.525 79.981 4.702 CD1 ILE 19 10.362 76.681 4.550 N ARG 20 10.369 81.764 7.648 CA ARG 20 9.967 83.160 7.870 C ARG 20 10.707 84.063 6.893 O ARG 20 11.537 83.519 6.130 CB ARG 20 10.349 83.584 9.300 CG ARG 20 9.573 82.818 10.384 CD ARG 20 8.086 83.272 10.386 NE ARG 20 7.308 82.535 11.412 CZ ARG 20 7.174 83.017 12.653 NH1 ARG 20 7.772 84.156 13.006 NH2 ARG 20 6.606 82.289 13.595 N TYR 21 10.399 85.366 6.904 CA TYR 21 10.990 86.415 6.062 C TYR 21 11.783 87.398 6.869 O TYR 21 11.415 87.709 8.041 CB TYR 21 9.927 87.254 5.321 CG TYR 21 9.227 86.344 4.286 CD1 TYR 21 8.248 85.445 4.687 CD2 TYR 21 9.646 86.387 2.959 CE1 TYR 21 7.676 84.603 3.763 CE2 TYR 21 9.069 85.549 2.012 CZ TYR 21 8.078 84.673 2.405 OH TYR 21 7.557 83.773 1.412 N PHE 22 12.796 87.894 6.215 CA PHE 22 13.615 88.967 6.804 C PHE 22 13.987 89.932 5.698 O PHE 22 14.116 89.477 4.531 CB PHE 22 14.907 88.520 7.581 CG PHE 22 16.075 88.032 6.669 CD1 PHE 22 17.134 88.870 6.407 CD2 PHE 22 15.985 86.820 6.026 CE1 PHE 22 18.117 88.510 5.493 CE2 PHE 22 16.971 86.465 5.087 CZ PHE 22 18.026 87.309 4.827 N TYR 23 14.114 91.168 6.073 CA TYR 23 14.585 92.201 5.205 C TYR 23 16.090 92.078 4.923 O TYR 23 16.917 92.192 5.837 CB TYR 23 14.153 93.589 5.740 CG TYR 23 14.412 94.670 4.674 CD1 TYR 23 15.332 95.661 4.931 CD2 TYR 23 13.831 94.573 3.433 CE1 TYR 23 15.673 96.561 3.951 CE2 TYR 23 14.126 95.511 2.461 CZ TYR 23 15.051 96.500 2.711 OH TYR 23 15.328 97.524 1.731 N ASN 24 16.465 91.884 3.687 CA ASN 24 17.855 91.855 3.252 C ASN 24 18.214 93.189 2.601 O ASN 24 17.796 93.529 1.451 CB ASN 24 18.069 90.729 2.240 CG ASN 24 19.546 90.661 1.887 OD1 ASN 24 20.363 91.402 2.468 ND2 ASN 24 19.880 89.455 1.644 N ALA 25 18.758 94.021 3.466 CA ALA 25 19.115 95.402 3.073 C ALA 25 20.153 95.346 1.943 O ALA 25 20.214 96.277 1.110 CB ALA 25 19.718 96.214 4.248 N LYS 26 20.926 94.294 1.871 CA LYS 26 21.927 94.209 .795 C LYS 26 21.316 93.971 −.576 O LYS 26 21.631 94.746 −1.505 CB LYS 26 23.192 93.345 1.081 CG LYS 26 24.224 94.036 1.988 CD LYS 26 25.450 93.125 2.200 CE LYS 26 26.558 93.805 3.024 NZ LYS 26 27.649 92.853 3.266 N ALA 27 20.301 93.136 −.638 CA ALA 27 19.535 92.893 −1.842 C ALA 27 18.417 93.896 −2.055 O ALA 27 17.769 94.008 −3.140 CB ALA 27 18.965 91.498 −1.663 N GLY 28 18.108 94.574 −1.014 CA GLY 28 16.876 95.398 −1.159 C GLY 28 15.598 94.564 −1.366 O GLY 28 14.605 95.041 −1.966 N LEU 29 15.540 93.437 −.697 CA LEU 29 14.302 92.689 −.621 C LEU 29 14.113 91.764 .573 O LEU 29 15.091 91.447 1.290 CB LEU 29 13.946 92.088 −1.983 CG LEU 29 14.560 90.736 −2.317 CD1 LEU 29 14.428 90.452 −3.825 CD2 LEU 29 15.947 90.475 −1.753 N CYS 30 12.929 91.251 .701 CA CYS 30 12.631 90.232 1.679 C CYS 30 12.973 88.827 1.225 O CYS 30 12.555 88.398 .118 CB CYS 30 11.200 90.387 2.252 SG CYS 30 10.933 92.009 2.993 N GLN 31 13.803 88.164 2.043 CA GLN 31 14.137 86.787 1.847 C GLN 31 13.585 85.869 2.933 O GLN 31 13.386 86.287 4.096 CB GLN 31 15.668 86.613 1.685 CG GLN 31 16.217 87.696 .795 CD GLN 31 17.411 87.066 .084 OE1 GLN 31 18.580 87.572 .152 NE2 GLN 31 16.976 86.163 −.802 N THR 32 13.640 84.623 2.640 CA THR 32 13.288 83.547 3.599 C THR 32 14.502 83.008 4.376 O THR 32 15.653 83.038 3.878 CB THR 32 12.607 82.379 2.857 OG1 THR 32 13.481 81.840 1.887 CG2 THR 32 11.287 82.754 2.182 N PHE 33 14.277 82.464 5.547 CA PHE 33 15.348 81.924 6.396 C PHE 33 14.664 80.984 7.337 O PHE 33 13.406 81.039 7.354 CB PHE 33 16.052 83.054 7.174 CG PHE 33 15.292 83.602 8.392 CD1 PHE 33 15.668 83.194 9.661 CD2 PHE 33 14.299 84.545 8.255 CE1 PHE 33 15.040 83.692 10.779 CE2 PHE 33 13.664 85.064 9.397 CZ PHE 33 14.036 84.631 10.661 N VAL 34 15.421 80.121 8.005 CA VAL 34 14.817 79.158 8.946 C VAL 34 14.792 79.652 10.385 O VAL 34 15.824 80.145 10.871 CB VAL 34 15.603 77.860 8.945 CG1 VAL 34 15.195 76.937 10.125 CG2 VAL 34 15.430 77.129 7.611 N TYR 35 13.618 79.811 10.941 CA TYR 35 13.427 80.274 12.288 C TYR 35 13.079 79.099 13.188 O TYR 35 12.406 78.147 12.731 CB TYR 35 12.330 81.337 12.313 CG TYR 35 11.870 81.698 13.742 CD1 TYR 35 12.758 82.213 14.672 CD2 TYR 35 10.537 81.529 14.090 CE1 TYR 35 12.316 82.567 15.958 CE2 TYR 35 10.082 81.920 15.351 CZ TYR 35 10.986 82.455 16.276 OH TYR 35 10.533 82.900 17.569 N GLY 36 13.843 78.988 14.257 CA GLY 36 13.813 77.777 15.086 C GLY 36 12.608 77.757 16.045 O GLY 36 12.258 76.684 16.583 N GLY 37 11.827 78.809 16.058 CA GLY 37 10.533 78.722 16.717 C GLY 37 10.571 79.339 18.109 O GLY 37 9.500 79.680 18.662 N CYS 38 11.653 79.933 18.487 CA CYS 38 11.521 80.813 19.692 C CYS 38 12.516 81.957 19.703 O CYS 38 13.609 81.759 19.130 CB CYS 38 11.705 80.016 21.020 SG CYS 38 13.319 79.230 21.236 N ARG 39 12.201 82.955 20.477 CA ARG 39 13.042 84.091 20.782 C ARG 39 13.345 84.908 19.525 O ARG 39 14.479 85.415 19.364 CB ARG 39 14.338 83.591 21.467 CG ARG 39 14.123 83.002 22.885 CD ARG 39 15.509 82.671 23.502 NE ARG 39 15.363 82.331 24.931 CZ ARG 39 16.144 81.403 25.524 NH1 ARG 39 17.181 80.838 24.899 NH2 ARG 39 15.926 81.022 26.767 N ALA 40 12.336 85.093 18.668 CA ALA 40 12.469 85.896 17.438 C ALA 40 13.003 87.295 17.694 O ALA 40 12.459 87.974 18.591 CB ALA 40 11.082 86.134 16.840 N LYS 41 13.780 87.825 16.770 CA LYS 41 14.069 89.246 16.766 C LYS 41 13.050 89.929 15.884 O LYS 41 12.110 89.279 15.385 CB LYS 41 15.514 89.487 16.297 CG LYS 41 16.414 88.775 17.308 CD LYS 41 17.893 89.161 17.266 CE LYS 41 18.524 88.784 18.640 NZ LYS 41 19.977 88.978 18.595 N ARG 42 13.185 91.205 15.759 CA ARG 42 12.207 91.986 14.989 C ARG 42 12.282 91.935 13.459 O ARG 42 11.214 91.904 12.783 CB ARG 42 12.066 93.440 15.465 CG ARG 42 11.365 93.469 16.839 CD ARG 42 11.248 94.923 17.264 NE ARG 42 12.630 95.393 17.419 CZ ARG 42 13.034 96.670 17.567 NH1 ARG 42 12.191 97.681 17.582 NH2 ARG 42 14.344 96.964 17.686 N ASN 43 13.432 91.638 12.944 CA ASN 43 13.534 91.297 11.513 C ASN 43 13.074 89.873 11.164 O ASN 43 13.896 88.965 10.939 CB ASN 43 14.973 91.612 11.028 CG ASN 43 14.962 91.773 9.511 OD1 ASN 43 13.867 91.977 8.926 ND2 ASN 43 16.144 91.851 8.961 N ASN 44 11.803 89.578 11.367 CA ASN 44 11.254 88.237 11.328 C ASN 44 9.754 88.326 11.025 O ASN 44 8.985 88.836 11.875 CB ASN 44 11.592 87.487 12.662 CG ASN 44 10.995 86.079 12.769 OD1 ASN 44 9.967 85.727 12.165 ND2 ASN 44 11.677 85.165 13.350 N PHE 45 9.338 88.074 9.788 CA PHE 45 7.939 88.332 9.277 C PHE 45 7.255 87.073 8.777 O PHE 45 7.934 86.052 8.515 CB PHE 45 7.943 89.381 8.158 CG PHE 45 8.609 90.681 8.657 CD1 PHE 45 9.962 90.922 8.445 CD2 PHE 45 7.851 91.618 9.326 CE1 PHE 45 10.538 92.109 8.899 CE2 PHE 45 8.433 92.808 9.759 CZ PHE 45 9.773 93.056 9.544 N LYS 46 5.953 87.013 8.850 CA LYS 46 5.307 85.750 8.528 C LYS 46 4.957 85.669 7.063 O LYS 46 4.816 84.538 6.573 CB LYS 46 4.008 85.607 9.317 CG LYS 46 4.338 84.938 10.654 CD LYS 46 3.144 85.117 11.573 CE LYS 46 3.348 84.392 12.912 NZ LYS 46 2.160 84.624 13.772 N SER 47 5.091 86.774 6.384 CA SER 47 4.904 86.776 4.924 C SER 47 5.754 87.843 4.273 O SER 47 6.210 88.797 4.983 CB SER 47 3.418 87.035 4.542 OG SER 47 3.126 88.431 4.812 N ALA 48 6.000 87.652 2.979 CA ALA 48 6.785 88.690 2.344 C ALA 48 6.089 90.062 2.370 O ALA 48 6.728 91.153 2.416 CB ALA 48 7.020 88.246 .910 N GLU 49 4.760 90.049 2.411 CA GLU 49 4.004 91.319 2.332 C GLU 49 4.141 92.115 3.621 O GLU 49 4.288 93.368 3.569 CB GLU 49 2.477 91.014 2.129 CG GLU 49 2.093 90.462 .742 CD GLU 49 2.593 89.033 .538 OE1 GLU 49 2.701 88.254 1.524 OE2 GLU 49 2.618 88.541 −.630 N ASP 50 4.098 91.367 4.747 CA ASP 50 4.316 92.036 6.061 C ASP 50 5.694 92.642 6.098 O ASP 50 5.807 93.832 6.441 CB ASP 50 4.244 91.148 7.311 CG ASP 50 2.836 90.713 7.693 OD1 ASP 50 1.831 91.183 7.108 OD2 ASP 50 2.725 89.630 8.316 N CYS 51 6.660 91.834 5.675 CA CYS 51 8.069 92.253 5.611 C CYS 51 8.278 93.500 4.739 O CYS 51 8.797 94.541 5.243 CB CYS 51 8.955 91.080 5.141 SG CYS 51 10.694 91.506 4.989 N MET 52 7.678 93.467 3.554 CA MET 52 7.777 94.629 2.704 C MET 52 7.113 95.861 3.268 O MET 52 7.730 96.945 3.202 CB MET 52 7.489 94.389 1.189 CG MET 52 8.547 95.004 .261 SD MET 52 9.677 93.778 −.404 CE MET 52 8.424 92.566 −.868 N ARG 53 5.939 95.729 3.847 CA ARG 53 5.276 96.896 4.444 C ARG 53 6.066 97.454 5.604 O ARG 53 6.260 98.691 5.654 CB ARG 53 3.886 96.462 4.982 CG ARG 53 2.861 97.572 5.264 CD ARG 53 1.424 97.032 5.029 NE ARG 53 1.279 95.906 5.894 CZ ARG 53 1.027 94.612 5.694 NH1 ARG 53 .686 94.084 4.520 NH2 ARG 53 1.167 93.823 6.747 N THR 54 6.627 96.618 6.444 CA THR 54 7.462 97.165 7.516 C THR 54 8.830 97.720 7.119 O THR 54 9.266 98.747 7.690 CB THR 54 7.674 96.154 8.624 OG1 THR 54 6.377 95.698 8.972 CG2 THR 54 8.395 96.794 9.843 N CYS 55 9.580 96.927 6.394 CA CYS 55 10.971 97.234 6.147 C CYS 55 11.291 97.818 4.797 O CYS 55 12.436 98.320 4.690 CB CYS 55 11.850 96.040 6.455 SG CYS 55 11.943 95.674 8.255 N GLY 56 10.514 97.479 3.790 CA GLY 56 10.957 97.710 2.392 C GLY 56 11.228 99.190 2.152 O GLY 56 10.367 100.002 2.539 N GLY 57 12.461 99.566 1.946 CA GLY 57 12.800 100.986 2.017 C GLY 57 13.886 101.219 3.058 O GLY 57 14.039 102.363 3.552 N ALA 58 14.615 100.141 3.414 CA ALA 58 15.722 100.266 4.422 C ALA 58 17.104 99.977 3.828 O ALA 58 18.036 100.786 4.093 CB ALA 58 15.483 99.453 5.728 OXT ALA 58 17.207 99.280 2.788

TABLE 50 Places in BPTI where disulfides are plausible Limit on Ca-Ca is 9.0, on Cb-Cb is 6.5 Limit on Ca-Cb is 7.5 Res#1 Res#2 A-A A1-B2 A2-B1 B-B ARG 1 GLY 57 4.90 4.71 5.20 4.62 PRO 2 CYS 5 5.56 4.73 6.17 5.50 PHE 4 ARG 42 6.11 5.43 4.91 4.02 PHE 4 ASN 43 5.93 5.38 5.59 5.44 CYS 5 TYR 23 5.69 4.53 5.82 4.41 CYS 5 CYS 55 5.62 4.59 4.40 3.61 CYS 5 ALA 58 6.61 5.09 5.38 3.84 LEU 6 ALA 25 5.96 4.80 6.50 5.10 LEU 6 ALA 58 7.10 5.97 7.10 6.11 GLU 7 ASN 43 6.52 5.07 6.16 4.91 PRO 9 PHE 22 6.21 4.65 5.66 4.14 PRO 9 PHE 33 7.17 5.63 5.76 4.21 PRO 9 ASN 43 6.41 5.63 7.07 6.40 TYR 10 LYS 41 6.45 5.62 5.14 4.27 THR 11 VAL 34 5.99 6.35 5.71 5.72 THR 11 GLY 36 5.18 4.80 5.31 4.75 GLY 12 CYS 14 5.88 6.43 5.56 5.75 GLY 12 GLY 36 5.68 4.66 5.29 4.55 GLY 12 CYS 38 6.34 6.80 4.90 5.49 GLY 12 ARG 39 6.17 5.49 4.83 4.35 CYS 14 ALA 16 6.13 6.47 5.95 5.93 CYS 14 GLY 36 4.65 3.79 4.68 4.25 CYS 14 GLY 37 5.54 5.42 4.48 4.32 CYS 14 CYS 38 5.57 5.08 4.47 3.92 ALA 16 ILE 18 5.88 5.79 5.30 4.86 ALA 16 GLY 37 5.46 4.38 4.48 3.27 ARG 17 VAL 34 5.77 5.23 6.39 5.57 ILE 18 ARG 20 6.34 6.36 6.44 6.18 ILE 18 TYR 35 5.01 5.09 4.90 4.68 ILE 18 GLY 37 6.53 6.42 5.35 5.33 ILE 19 THR 32 6.30 5.79 6.04 5.18 ARG 20 TYR 35 6.31 5.35 5.42 4.25 ARG 20 ASN 44 6.28 6.66 5.16 5.30 TYR 21 CYS 30 6.04 5.51 5.43 4.57 TYR 21 PHE 45 4.83 4.74 4.56 4.06 TYR 21 ALA 48 6.06 6.76 4.56 5.38 TYR 21 CYS 51 6.54 5.17 5.34 3.95 PHE 22 PHE 33 7.26 6.41 6.72 5.60 PHE 22 ASN 43 5.25 5.17 5.01 4.63 TYR 23 ASN 43 6.46 5.87 6.24 5.70 TYR 23 CYS 51 6.53 5.74 6.23 5.80 TYR 23 CYS 55 6.27 4.88 4.86 3.44 TYR 23 ALA 58 8.18 7.33 6.98 6.01 ASN 24 ALA 27 5.46 5.05 4.85 4.08 ASN 24 GLN 31 6.44 5.89 5.58 4.80 ALA 25 ALA 58 6.08 6.05 5.69 5.53 ALA 27 LEU 29 5.38 5.65 4.92 5.06 CYS 30 ALA 48 6.08 6.00 4.73 4.88 CYS 30 CYS 51 6.35 5.12 4.96 3.72 CYS 30 MET 52 6.63 6.63 5.47 5.56 TYR 35 ASN 44 8.31 7.45 7.05 6.20 ALA 40 ASN 44 6.65 5.11 5.90 4.42 LYS 41 ASN 44 6.21 5.11 6.66 5.71 PHE 45 ASP 50 6.10 5.04 4.96 4.19 PHE 45 CYS 51 5.37 5.07 3.84 3.61 LYS 46 ASP 50 6.83 5.63 7.21 5.90 SER 47 GLU 49 5.31 5.63 4.86 4.75 SER 47 ASP 50 5.41 5.02 5.30 5.03 MET 52 GLY 56 4.44 3.58 4.95 3.71 CYS 55 ALA 58 5.89 5.05 6.08 5.04

TABLE 55 Shortened Kunitz domains to bind plasma kallikrein

TABLE 100 Sequence of whole LACI:   1 MIYTMKKVHA LWASVCLLLN LAPAPLNAds eedeehtiit  dtelpplklM  51 HSFCAFKADD GPCKAIMKRF FFNIFTRQCE EFIYGGCEGN  QNRFESLEEC 101 KKMCTRDnan riikttaqqe kpdfcfleed pgicrgyitr  yfynnqtkqc 151 erfkyggclg nmnnfetlee cknicedgpn gfqvdnygtq  lnavnnsltp 201 qstkvpslfe fhgpswcltp adrglcrane nrfyynsvig  kcrpfkysgc 251 ggnennftsk qeclrackkg fiqriskggl iktkrkrkkq  rvkiayeeif 301 vknm (SEQ ID NO: 25) The signal sequence (1-28) is uppercase and underscored LACI-K1 is uppercase LACI-K2 is underscored LACI-K3 is bold

TABLE 103 LAC1-K1 derivatives that bind and inhibit human plasma Kallikrein 13 14 15 16 17 18 19 31 32 34 39(a) KKII/3#1 (SEQ ID NO: 2) H C K A S L P E E I E KKII/3#2 (SEQ ID NO: 3) P C K A N H L E E S G KKII/3#3 (SEQ ID NO: 4) H C K A N H Q E E T G KKII/3#4 (SEQ ID NO: 5) H C K A N H Q E Q T A KKII/3#5 (SEQ ID NO: 6) H C K A S L P E E I G KKII/3#6 (SEQ ID NO: 7) H C K A N H Q E E S G KKII/3#7 (SEQ ID NO: 8) H C K A N H Q E E S G KKII/3#8 (SEQ ID NO: 9) H C K A N H Q E E S G KKII/3#9 (SEQ ID NO: 10) H C K A N H Q E E S G KKII/3#10 (SEQ ID NO: 11) H C K G A H L E E I E Consensus H C K A N H Q E E S/T G Fixed C K Absolute E Strong preference H A H E Good selection N Q G Some selection S/T

TABLE 202 vgDNA for LACI-D1 to vary residues 10, 11, 13, 15, 16, 17, & 19 for  pKA in view of previous selections.

DNA: 131,072 protein: 78,848

TABLE 204 Variation of Residues 31, 32, 34, 39, 40, 41, and 42 for pKA in view of previous selections.

There are 131,072 DNA sequences and 70,304 protein sequences.

TABLE 220 Cα-Cα distances in P1 region of BPTI T11 G12 P13 C14 K15 A16 R17 I18 I19 R20 G12 3.8 P13 7.0 3.8 C14 8.0 5.9 3.9 K15 8.9 8.2 6.5 3.7 A16 9.5 9.9 9.4 6.1 3.8 R17 9.1 10.9 11.4 8.9 6.5 3.8 I18 9.2 11.3 12.7 10.3 9.0 5.9 3.8 I19 10.0 12.9 15.1 13.4 12.2 9.5 6.6 3.8 R20 9.6 12.6 15.4 14.2 14.1 11.7 9.6 6.3 3.8 Y21 11.2 14.4 17.7 17.1 17.3 15.3 13.0 10.1 7.1 3.9 Q31 13.6 17.2 20.5 20.5 20.1 18.4 15.5 13.4 9.9 8.2 T32 11.2 14.9 18.0 17.4 16.7 14.9 11.8 9.8 6.3 5.4 V34 6.0 9.4 11.6 10.8 9.8 8.5 5.8 5.5 5.0 6.4 Q31 T32 V34 T32 3.8 V34 10.4 7.1

TABLE 1017 High specificity plasma Kallikrein inhibitors LACI-K1 MHSFCAFKADDGPCKAIMKRFFFNIFTRQCEEFTYGGCEGNQNRFESLEE CKKMCTRD (residues 50-107 of SEQ ID NO: 25) KKII/3#7 MhsfcafkaddgHckANHQrfffniftrqcEEfSyggcGgnqnrfeslee ckkmctrd (SEQ ID NO: 8) KKII/3#7-K15A mhsfcafkaddgHcaANHQrfffniftrqcEEfSyggcGgnqnrfeslee ckkmctrd (SEQ ID NO: 31)

REFERENCES CITED

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1-6. (canceled)
 7. A kallikrein inhibiting protein comprising a non-naturally occurring Kunitz domain, said Kunitz domain having disulfide bonds at Cys5-Cys55, Cys14-Cys38, and Cys30-Cys51 and further having: amino acid number 13 selected from the group consisting of His and Pro; amino acid number 14 as Cys; amino acid number 16 selected from the group consisting of Ala and Gly; amino acid number 17 selected from the group consisting of Ala, Asn, and Ser; amino acid number 18 selected from the group consisting of His and Leu; amino acid number 19 selected from the group consisting of Gln, Leu, and Pro; amino acid number 31 as Glu; amino acid number 32 selected from the group consisting of Glu and Gln; amino acid number 34 selected from the group consisting of Ser, Thr, and Ile; and amino acid number 39 selected from the group consisting of Gly, Glu, and Ala, wherein the above amino acids are numbered to correspond to the numbering of amino acid residues of bovine pancreatic trypsin inhibitor (BPTI) (SEQ ID NO:1), and wherein the protein binds plasma kallikrein with a Ki less than 500 μM.
 8. The protein of claim 7, wherein one or more of the amino acids in the protein is chemically modified.
 9. A pharmaceutical composition comprising the protein of claim 7 and a pharmaceutically acceptable carrier.
 10. A method of treating a disorder attributable or exacerbated by excessive or otherwise undesirable kallikrein activity comprising administering to a subject who would benefit therefrom, the protein of claim
 7. 11. A method of reducing kallikrein activity in a subject in need thereof, comprising administering to the subject the protein of claim
 7. 12. A method of assaying for the presence of kallikrein in a sample comprising providing the protein of claim 7 in labeled or insolubilized form, contaicting said protein with said sample, and determining whether a complex of said protein and kallikrein in the sample is formed.
 13. A method of purifying kallikrein from a mixture, wherein the method comprises providing the protein of claim 7 in insolubilized form and contacting the mixture with said insolubilized protein so that kallikrein in the mixture is bound.
 14. An isolated polynucleotide encoding a kallikrein inhibiting Kunitz domain protein, which protein has an amino acid sequence selected from the group consisting of SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:31, SEQ ID NO:32, SEQ ID NO:64, SEQ ID NO:65, and SEQ ID NO:66.
 15. An in vitro method of assaying a sample for a substance that binds plasma kallikrein (pKA), wherein the method comprises allowing the binding protein of claim 7 to compete for binding to the substance.
 16. The method of claim 15, wherein the binding protein is immobilized to a solid support.
 17. The method of claim 16, wherein the solid support is glass, polystyrene, polypropylene, polyethylene, dextran, nylon, amylase, or magnetite.
 18. The method of claim 15, wherein the binding protein is labeled.
 19. The method of claim 18, wherein the label is a radioisotope, a fluorophore, an enzyme, a co-enzyme, an enzyme substrate, an electron-dense compound, an agglutinable particle, a fluorescent compound, a fluorescence-emitting metal, a chemiluminescent compound, or a bioluminescent compound.
 20. The method of claim 18, wherein said radioisotope is selected from ³H, ¹²⁵I, ³⁵S, and ¹⁴C.
 21. A method for in vivo imaging of excess plasma kallikrein activity comprising administering to a subject the protein of claim 7, wherein said protein is radiolabeled.
 22. The method of claim 21, wherein the radiolabel is ¹²³I, ¹²⁵I, ¹³¹I, ^(99m)Tc, ⁶⁷Ga, ⁹⁰Y, ¹¹¹In, ^(113m)In, ¹⁸⁶Re, ¹⁸⁸Re or ²¹¹At.
 23. The method of claim 21, comprising detecting analysis of radioactivity over time in a target organ.
 24. The method of claim 21, wherein the radiolabeled pKA binding protein is administered intravenously, subcutaneously, or intramuscularly.
 25. The method of claim 21, wherein the subject is a human.
 26. A method for in vivo imaging of excess plasma kallikrein activity comprising administering to a subject radiolabeled kallikrein binding protein KKII/3#6. 